During the train ride before third year Harry has a close encounter with a dementor that causes him to absorb the soul fragment within him, granting both knowledge and power. Features Harry with a ...
I I I
After 'Normal Day' came 'Resource Day', the day for building up abilities and marshaling resources for dealing with the future conflicts.
Mostly, they'd intended this for the very simple reason of they needed to be stronger. So they'd decided to spend this extra time on developing personal skills, expanding that most critical of all resources - themselves.
However, today was turning out a little differently.
Mostly because they'd all been bombarded at the end of the 'Normal Day'before this by a recitation of all the various ways the world they lived in resembled some books by Tolkien. And one of those suggestions that had nothing to do with Hobbits, the French, or dementors, was that the dwarves of the modern wizarding world were the dispossessed descendants of those ancient, famous rulers of mountain halls.
And, well, that had struck an awfully familiar chord in everybody (and the first paper to suggest that got an O+ by Hermione).
They knew that dwarves existed. Lockhart had used them to deliver singing Valentines the previous year, a degrading job that had everyone involved most desperately embarrassed.
They also knew that the dwarves of their world had once enjoyed greatness. They'd been the fallback plan for cleansing the Cauldron of Blood simply because it was a known fact that dwarves were that good, they COULD cleanse an ancient artifact of that level of power of a taint so deep. They had, after all, made it in the first place.
But you don't give someone a humiliating job doing something degrading like delivering valentines nobody wants if he's got some dignity, or anything else he could do - something like, oh, say, making or repairing magical artifacts, or tending his mountain halls.
So the simple fact was the dwarves of the magical world were a fallen race. Where once they had enjoyed greatness, now they were the dispossessed, the dregs, huddling in those corners no one else wanted.
To Harry that simply screamed 'Opportunity'!
It was a formula that had been pulled countless times before, by just about every leader of their world: find some downtrodden group to champion to get yourself instant followers.
Vulturewart had done this for dark creatures like dementors, vampires and hags. Dumbledore had set wizard against wizard, then made himself indispensable to both sides of the conflict he himself had created.
No sooner had they finished grading the school's History homework than Harry was already resolved to see if he couldn't court some support among the dwarves, and was already halfway done with some plans for doing so.
One reason no one else had done this was the dwarven race was both proud and stubborn. Too stubborn to accept charity, and too proud to let themselves be treated as the underclass they had effectively become. So anyone looking for eager sycophants or bootlickers was more likely than not to simply walk away with the imprint of a boot low on his backside.
Dwarves did not toady.
That was fine for Harry. He wouldn't have wanted toadies anyway. That was what vulturewart and Dumbles wanted, and they'd pretty much sewn up the available supplies between them. Besides, look where it got them. Both had to be constantly checking their backs, and wary lest another man step in with a bribe to steal their followers away from them. Tom Riddle was not a hero to the vampires. He was simply a man offering them something they wanted. If someone came along offering something they wanted more, the night clans would be out of his service faster than he could say, "Who farted?"
No. Recruit sycophants and you got what you paid for. Mercenaries, the lot of them.
Dwarves, on the other hand... well, they were famous for recalling grudges forever. But they also never forgot any of their friends. Do a favor for them and it got repaid, even if they had to bathe a kingdom in blood to do it.
Of course, that grudge thing... you don't get away with betraying adwarf. Ever. So for those for whom sneaky and underhanded dealing was away of life, they were just too volatile to consider using for their ends. Better to take on championing those races who expected to be betrayed. It was safer.
Harry, who had no intention of betraying anybody if he could avoid it, simply checked into Sweden.
They had low population density and about eighty five percent of their people lived in urban areas. That made them easy to avoid for someone who wanted to set up secret magical preserves in the hinterlands. Not to mention it was a mountainous, rugged country and some of those out of the way places were so hard to get to they were probably among the most isolated spots on Earth. Not impossible to get to, but unlike the Himalayas, people rarely tried.
"I backpacked through the wilds of Sweden" just doesn't have the same ring as "I climbing Everest again this year." Although, objectively speaking, the only thing that could make climbing Everest any more tacky these days was if they installed an escalator to the top and put a Starbucks on the summit. Everest climbers were literally stumbling over piles of each other's trash as they went up and down.
That meant there were plenty of blind spots in the mountains of Sweden to include something secret. Say, even something magical.
There were plenty of mines in Sweden. But nothing that could be mined there couldn't be mined elsewhere, and usually cheaper. But that was the same for all of the developed countries, and the usual games got played there to keep the domestic production going.
But one inevitable fact of mining was that Mines Run Out. There's only so much metal in them thar hills and sooner or later one particular pit doesn't pull enough of whatever out to pay for the costs of getting it. So they stop paying it and close the mine.
However, 'worth it' has a different meaning to corporate execs who have to balance labor and shipping costs, machinery breakdowns and social welfare benefits, than it does to, say, dwarves, who'd like to live there and use the ore themselves for their own purposes.
So, Harry bought himself a played out mine.
He had several of those already, through the Black family holdings. But those were in England, and the boy's whole objective lately was to get his resources moved out of that country, as it Dumbledore's prime zone of control.
Besides, it felt nice to do, as dwarves were a very Scandinavian race, and Sweden was one of their ancient homes. It would be a good spot for them to have a new home. They could turn the mine into a mountain hall themselves, and, in fact, would prefer to do so. Other people couldn't get it right.
Also, land was the ultimate source of wealth. Having land, like a played out mine, skills and the willingness to build, could put the dwarven race on the road to recovery.
By going through muggle channels he was able to use muggle currency, which even if he went his fastest at it and did nothing else, he couldn't conjure it as fast as the actual banks and governments were doing. So no harm done.
As iron was one of three principle portions of the Swedish resource base, the country had a lot of played out mines to choose from. So it wasn't any particular problem to get one in a nice, remote area.
Then he offered a deal to the dwarves. "This mine is worth X. Since I want to hire you for a building project, how about I trade you this mine for X amount of materials and labor?"
Then, when it turned out they had no materials to trade (their race had gotten THAT poor), that became, "Well, how about X amount of labor divided among harvesting the resources I need from my other properties and assembling those into the final product I desire?"
The final product?
Simple. He was making a town, and wanted the dwarves to build the houses at Godric's Hollow.
I I I
When building a town it helps to know what you want to build.
Harry wanted Godric's Hollow to be safe. And, building it up from the ground in most cases, he had opportunities to do so like no one else had had in ages. Also having the skills of a renowned curse breaker turned home invader gave him knowledge like few others. In particular, it helped him understand the many mistakes most wizards made so he could avoid them.
In the first place, wizards, when they dealt with security at all, took to it as an afterthought. Defensive wards, where they existed at all, were applied to whatever ramshackle huts they were living in at the time.
The Weasleys were an extreme yet very good example of this. That house of theirs barely held together at all. It was a crazy structure that couldn't exist without magic supports, and you could put only so many wards on ahouse. So spending some of your precious allowance of that potential on structural wards holding up walls too crazy to exist without magic meant you had that much less capacity to spend on defensive wards for making yourself and your family safe from things like Death Eater attacks.
So, if you should take the remarkable step of actually building a structure that could stand up on its own without help, you didn't have to weaken your capacity for defensive wards in order for that house to simply exist.
A remarkable thought, no? You wouldn't think so, but most wizards were so batty they verged on completely insane. To them this would be a completely revolutionary concept.
Of course, with magic you didn't often have to think ahead. If a dress did not fit because you'd gained FIVE DOZEN sizes since last wearing it, it could still be made to expand with charms, and it's out on the town with you. Left your wallet at home? Apparate back to get it in a second. Forgot to close the barn gate and the cow got out? Summon it. Not enough plates at the dinner table for all the guests you invited? Conjure more. Broke something foolishly? One quick Repario and it's all better. You are an odious person with foul personal habits offensive to the opposite sex?Try a love potion. Anyplace you are, anything you want can most likely be transfigured out of handy garbage to fill a temporary need. Or if not, Confound a shop clerk to get it.
Wizards were used to magic adapting whatever they had to create solutions. No matter the problem, wave your wand to fix it. Granted, there were afew exceptions, and morals got in the ways sometimes, but they had no NEED for common sense in most cases!
So, by and large, they never developed any.
The strange thing was, that WORKED for them in most instances! So wizards could afford to be incompetent imbeciles, because in most cases they lived a life completely free of the consequences of bad planning, poor thinking, and an extreme lack of common sense. Magic was so flexible that it could save people from the consequences of their stupidity almost every time.
And, the natural result of people raised without consequences for stupid actions was they never learned to overcome their stupidity. It gave you a nation full of fools.
The major reason for the pureblood craze was: among wizards that practice worked. They could afford to be fools and not get hurt for it. And up against muggles magic proved to be enough of an advantage that it still worked. But against those muggle-raised able to use magic?
It failed every time.
Muggleborns had both magic and common sense, the best of each. That gave the magic-raised a deep seated fear of the muggleborn witches and wizards. Clear-thinking spell-users frightened the magic-raised of Europe.
Probably why people had been so scared of vulturewart in the last war, even if they didn't know it. Before he dipped himself so deeply in pureblood ways, he'd been one of those clear thinking magic users they feared so.
But Harry didn't care two knuts for that fear and was going to be applying the advantages of muggle thinking to the magical problem of home defense. And in the first place, that meant building roomy structures - because otherwise the wizards who moved into them would want to be adding a new bathroom on the fourth floor with nothing under supporting it, and so on until they'd assembled enough insane bits to make another Weasley home.
So if the homes were big to start with the wizards couldn't scream as much when he said they couldn't add expansions onto them magically.
Actually, along the lines of a defensive structure already strong enough to need little in the way of magic to defend, one of the ideal layouts was already centuries old, that of the fortified suburban villa.
A square structure four or five stories tall, enclosing a courtyard in the center that you then capped with an arched ceiling made out of blocks of transparent stone - or even a dome enchanted like the Hogwarts Great Hall's ceiling to let the light through. Solid brick and masonry had stood up as one of the most enduring construction styles over time, and good thick walls didn't have to have as much magic protecting them to keep the bad guys out. Dwarf-built structures were even stronger, and the more strength you got through basic properties the less you had to add via magic.
The courtyard was also an excellent idea. That way the kids could run and play out on the grass under trees without leaving the confines of the house out where marauding bands of vampires or Death Nibblers could get at them.
Give them reasons to stay inside. Make it convenient to stay safe and they are more liable to do so. Then put wide lawns between villas so that they had clear fields of fire so those within could shoot people approaching the house.
A place that size could easily sport a dozen bedrooms, several sitting rooms, a ballroom and library. The design was intended for spacious, aristocratic living. Rather more than a single family needs, but considering that with the dangers of the recurring wars it was better to stay indoors under protection than go out too often, it was better to have too much space than too little. Even add a principle or two adopted from the middle-class Roman Domus and add space for a shop or two opening out onto the street.
No one defense would stop everything. But a good, strong, solidly built stone house was an excellent point to start off with. Already tough, they could be magically strengthened yet further and made very highly resistant to most harmful spells. Tile roofs and little or no exposed timber left nothing to burn, so fire (one of the most frequently used weapons in warfare)was less dangerous. A house-sized variant of the bubble-head charm could even be developed if he felt poison gasses were a danger.
Sections of Europe had, during some of their more difficult and turbulent periods, gone through styles where they'd studded their wooden doors with metal spikes. They looked decorative. In fact most people never realized what they were for. But you did that so no one would try to break down your door with his shoulder, and it greatly complicated chopping through the thing with axes. So, if you worried about those, spiking your doors was a good idea.
Harry was concerned about those, so he spiked the doors. He wasn't so much afraid of wizards trying to brute-force their way through. No, smashing in a door with their bodies was far too physical, they'd prefer to use spells to gain a forcible entry if that's what they wanted. But he was concerned about werewolves. There were a lot of them in England, desperate enough they were willing to follow anyone who promised them even a hint of freedom, and clawing through doors lay exactly within their temperament and abilities.
So Harry not only spiked the doors, he used a magic process that effectively electroplated those spikes with silver (and laid down spells so the thin plating would not wear off during use). Then, because werewolves were not the only physically strong magical race with a penchant for following dark lords, he crafted each of the base plates of those spikes into silver crosses, to help keep any vampires out.
You could never be too careful about that sort of thing.
Speaking of careful, he did the same silver plated cross motif with all of the door handles, window latches, window shutters (shutters that could be closed from inside the house, and spiked for the exact same reasons as the doors) and just about all other 'grab this to obtain access' parts of those villas.
It would make living there practically impossible for people like Remus. But if you couldn't make it safe for him AND everyone else, first make it safe for everyone else. He could be dealt with as a special case, and he was the only werewolf Harry knew of who wasn't at least partially complicit in dark lord worship... No. That had to be retracted. The man served Dumbledore. So in spite of the innocence of his intentions, perhaps it was best to keep him out.
No hard feelings, just trying to create a place safe for the rest of us. Remus wouldn't be in any more danger than he already was, but everyone else could be made that much safer.
And werewolf attacks were a big problem during the last war, so they had to have a defense against them. Sorry, that was just the way it was.
That left giants and dementors as major threats to be dealt with. Dementors could and would be kept out by the town wards. Harry couldn't think of any good reason for them ever to go there, and so he'd already built his wards so those nightmarish wraiths were deliberately and specifically excluded. And muggles had gotten one or two things right in their folklore. Dementors were one of surprisingly many dark creatures driven off by the sound of church bells. So Harry planned to build a few churches just so he could put bell towers in them.
Giants, on the other hand, were a threat not easily stopped by wards, and couldn't care less about bells. There were spells, however, for strengthening stone walls and things to better survive the kind of damage they dealt. The buildings would have to be built strong to start with, as those spells only magnified what strength you already had, but that was his intention anyway.
And, while giants could not easily be stopped by wards or bells, there were counters for them too. Dementors did not care about physical guardians, but giants could be quite effectively dealt with by guardian statues.
Giants were big and tough and strong, but stone statues could always be built bigger and tougher and stronger, especially with toughness and strength increased by those same spells that magnified the strength of buildings.
Giants were the tanks of magical battlefields. But tanks could be stopped if you were prepared to deal with them beforehand. One of the best ways was always to build your own tanks. So, stopping giants with guardian golems was just something he planned to do.
Of course, once you stripped away all of the helpful followers, dark wizards would still be a problem; even if they couldn't march in behind ranks of allied werewolves, vampires, giants or dementors. In fact, one of their favorite strategies would be to crack open the defenses themselves, then send in those same allies once they'd put a stop to the measures keeping them out.
Then again, dark wizards were bullies. Their idea of a fair fight was to pull some dirty trick to get you helpless before them, then torture you. They were not big fans of being in the least kind of danger themselves.
They'd try to get into those houses on some pretext or other, then start their mayhem inside, catching their prey by surprise and without defenses.
So you adopt a Victorian concept. This wasn't hard to do, as wizards were already living in a largely pre-Victorian age in most ways, so it was a fairly painless process to propose.
A Victorian House had two parlors, a guest parlor and then a family one. When guests came over they saw only the entry hall and the guest parlor. They were not permitted into any other part of the home. It just wasn't done. If you were a very, very close friend, they might invite you into the family parlor, and this was taken to mean that you were as close as family; but you still weren't permitted up into their bedrooms or other'family only' areas of the house.
Perhaps the division did not have to be that extreme. Let your guests roam over the whole ground floor of your house, into the atrium, ballroom, even the workshops. Just ensure that the ground floor was all they could reach.
If an enemy NEVER got up into your private quarters it was hard for him to lay nasty traps for you up there. Everyone needs a safe place, aplace to be secure so they can rest and recuperate. The Death Nibblers had that by fraud, wearing masks and saying, "Oh, WE'RE not the people hurting you! It isn't US!" so their homes were inviolate as they rarely got charged for their crimes. As soon as they took the masks off they were safe from reprisal.
Other people... well, since the terrorists under vulturewart didn't care to let the same rules that protected them protect others, you had to keep them out by main force.
Harry knew he'd mocked wizards for hiding behind wards, turtling up to avoid having to face a threat, but the fact of the matter was you could not defend against magical attackers without magical defenses. If he could blow through your walls with a Reducto curse it didn't matter what you'd done to bar the door, so to speak. So defensive wards were a simple necessity.
However, to maximize the benefit of the wards, you don't sap their strength by doing stupid stuff with them, and one of the most stupid things to avoid was slapping them onto a weak structure - or a poorly designed one.
Building a defensible home shared many of the same principles as building a secure vault, or secure anything. The first principle of defensive structures was 'make it hard for an enemy to access'. And, for a magical house, that included cutting off or restricting magical means of entry.
Since wizards were almost the epitome of stupid, and would be inviting guests over and holding balls or opening shops, all of which provided aflood of opportunities to sneakily insert polyjuiced agents or assassins in, Harry decided that each of these homes, small fortresses really, he was building in Godric's Hollow ought to have two alert statuses: relaxed and vigilant.
The relaxed state would be just that: low security so those stupid, stupid people could go about their lives with a minimum of fuss and bother, letting near total strangers into their homes and so on. Even in that state he would insist on protections for keeping all but family (and family servants)out of the 'family only' areas of the house. But they could still have all the guests they wanted over on the ground floor.
The vigilant alert status would be for when it struck those bone-thick skulls of theirs that there were Death Eaters out there on raids killing people, and they'd want to button up tight to avoid being on some vampire's menu for the evening, or having some werewolf nibbling on their children.
But, of course, some general protections would apply during both.
Anti-apparation and anti-portkey wards were the start (really, those were the same thing. A portkey was just a set-destination apparation stored in an object, just like a potion could sometimes be called a spell in abottle). But that didn't even cover half of it. The next step was to put the floo access in a separate outbuilding. Connect it by a covered walk, so it wasn't unpleasant to use even in bad weather; but if you are going to get attacked by wizards arriving through your floo, have them arrive in a gazebo a short distance away from your home instead of in your living room.
So called 'secure' floo systems were nothing of the sort. They were either made that way by the ministry department regulating them (and which the Death Eaters had agents in since the first war, to undo those protections at need) or they were merely warded like any other entrance. And anything you could put a ward on, someone else could break the ward on; and with the ability to floo-call, sticking only your head (and hands, if you wanted)through a fire to someone else's floo, an invader could be working on breaking your wards from a thousand miles away without you even knowing of it.
If the floo was in a separate outbuilding, without even any fireplaces inside the main house, breaking the wards was just the first step, especially in the case of a gazebo, where visibility all around meant anyone around could see someone's head and hands poking through and sound the alarm.
If there was even a fireplace inside the main building, that could be hooked up to the floo by that same ministry department the Death Nibblers had agents in. So you instead rely on central heating and do away with fireplaces entirely - leaving the gazebo the only place you could floo to or from.
They made them beautifully, a single central pillar style chimney with an open faced fireplace large enough to walk into without stooping down. They made it facing a gap in the six sided gazebo where the railing did not extend, so a witch or wizard in a hurry would not have to pause on their way in, or worry about striking their heads on a railing on their way out. They even made some with multiple fireplaces for those who wanted to do a lot of floo traffic. In fact, they made triple fireplaces on ashared central chimney standard so a young witch could still go to market while her Aunt Edna was floo-calling some of her friends and mom was on the line with someone else.
It cost virtually nothing to build the extra fireplaces from the get-go, and it was really a remarkable convenience, which did a lot to make up for having to leave your house to use it. They also looked a bit like an outdoor barbecue built into its own convenient structure.
Then back to the main house. Your entry points are your weak points, and an enemy was going to try to access them just as you did. The trick there was to make it easy and convenient for yourself, but as close to impossible as you could devise for your enemy.
One of the first things to do is grant yourself sort of a gatehouse approach where each of the entrances or exits to your home was actually a small room with two doors, like an airlock. One led into the house proper, one led into the outside world. In the middle you put a place to hang cloaks and put up muddy shoes so it looked merely like a place for donning or doffing winter garments without tracking snow in over your nice carpets, and to help keep out drafts.
You do the same with all of your staircases, or other means of reaching anything but the ground floor, to seal off your private areas. And most of the time people had no reason to suspect this was anything other than an interesting architectural feature, something quaint and rustic to slow the spread of fires or to keep down drafts.
That was the illusion. The reality was that they did do all those things, but the design was also capable of serving a far more sinister purpose.
During low security times you could open both doors of the house entrances and leave them that way so customers could enter your shop or guests could come to your balls, or whatever. And it would be just as easy or convenient as anything else.
The stairway equivalents of the same thing would stay sealed at all times except to authorized family members and servants, and it would stay not only safe but convenient because most people had no real legitimate excuse to go into those areas anyway.
Then, during lockdown, you expel the guests and seal up all your entrances. No one stays inside that you don't trust to fight alongside you instead of against you, and given the prevalence of polyjuice and imperious curses, it was safer to send even those types away to their own homes anyway.
It was foolhardy to have untrustworthy elements inside your defenses when it came time to fight or die. But it was important to lay down the policy in clean, crisp clarity, because given their druthers, wizards would be fools.
But because it was unfriendly to fling your guests out the door and straight into the teeth of an invading army, they'd have to establish policies to enact lockdown in an atmosphere of danger, rather than at the very last second when you could already see the enemy on his way.
That meant he'd probably be forced to erect public dance halls and buildings where everyone was a guest, and no one would get expelled, because they wouldn't stop having parties just because people were trying to kill them.
And... that naturally meant those public parties would be the first choice of every Death Eater for a place to attack. And they'd start each attack by having people on the inside as invited guests start flinging curses. And then the witches and wizards holding those parties would wonder how it happened.
Bloody idiots. Sometimes he had to wonder if it was worth saving these fools.
But back to the houses, where hopefully at least some portion of these imbeciles would eventually learn to take cover. The outer door of the home's entranceways was what an invading enemy was going to hit first. So you put no more than average defenses on them, as whatever you put there they are going to analyze and expect, and thus break through rather quickly.
So you set the outer door with something simple, expected, either akey or a passcode (or, for better security, both). The key could be stolen, summoned, or copied, while spoken codes could be gotten by Imperious, or just by agents standing by under invisibility cloaks or similar, listening as you used them.
You don't worry too much about him getting in the outer door. Your strategy depends on it. From there, however, it becomes twofold: don't let him in the inner door, and don't let him out again either. So, in the first place, you set it so whatever key or code gets a person in WON'T get him out again!That puts him up against the full strength of the walls and wards without an easy out.
Trapped like that, you could destroy him at your leisure. Whether that was to call in Ministry aurors to haul him away, or to deal with yourself, once you had him trapped he was in your power to do with as you chose.
Of course the problem lies in keeping them there. Once they realize they're trapped they won't want to stay. They'll use every device and skill at their disposal to escape (either in to hurt you or out to safety).
The simplest things are the easiest to make reliable. There are more ways to break delicate clockwork than a simple brick wall. This applied to magic as well. Any wards could be broken. But most wards could NOT be broken by most people, and even then the stronger your wards the fewer could break them, especially on short notice.
Wardstones had a certain capacity, and even supported by appropriate runic amplifiers they could only hold so much of a burden of spells. Decision-making portions ate up a ton of that capacity, so wards that didn't have to make choices could be much, much stronger than those that did. And the more complex those decisions had to be, the more capacity they ate, and the more flaws those introduced, so the weaker your warding scheme overall.
Of course, wizards set wards as they did anything else - with an eye toward their own maximum convenience. "Well, let my family enter, and of course my friends, and let me change who my friends are, and..." Such award scheme, to be completely unobtrusive, had to not only track by blood relation, but the whims and vagaries of emotions out of all those members. That tied up a terrible amount of capacity to serve simple convenience.
Harry's answer was simple: don't have the wards make any choices at all unless you absolutely had to.
Say instead, "Those I invite are welcome. Those I don't aren't." It was not much less convenient. All it required was to recall a single step, and not an impolite one. But rather than trying to keep a ward busy reading your mind for just how you felt about someone on a certain day, taking over that responsibility yourself made for far more powerful protections.
That pattern continued. The more choices about who entered and who did not you made yourself, the more power those wards could focus on keeping you safe rather than being your own personal, magical mood ring, until it was almost impossible even for someone of Vulturewart's skill and power to break and gain entry. Particularly on short notice.
And, if the outer door has an entry code that's easy to overhear or guess, he won't think he has to break down your wards to enter your house. So he won't come prepared to do so - that requires work, and most wizards(but ESPECIALLY dark wizards) are lazy, not doing any work they don't have to.
So, you trap him. And in the first place, you set it so that none of the doors leading inside from the isolated little entrance halls could be opened from the outside during lockdown if there was any family member home at all.
That put it up to a person to decide whether or not to let whoever it was at the door in or to drop some nasty trap on them.
Of course, before you pour sixty tons of boiling hot sand on his head you want to know whether this intruder was a pushy salesman or a murderer, or just your dad returning from work but lost his keys.
Or, for the upcoming war, you had to know if that WAS your dad, but under Imperious. Or just possibly someone under polyjuice to only look like a family member. Those were very real dangers because all of those things had happened during the last war, and the same baddies were going to come back to do it again the next time.
Those strategies had been effective for them, so they'd use them again.
So you hang a Foe Glass at head height right beside every door opening to an entranceway, in a place where you can't help but glance at it as you go to the door. Then you also put a peephole through the door itself, and tell people, "If the face you see in that Foe Glass is the face of the person on the other side of that door, you don't open it no matter who it is. They could be your wife, your parent, child, even your long lost aunt. If they show up in the Foe Glass, they are your enemy. That might be because they could be under Imperious, or they could be using Polyjuice, but whoever it is they are not your friend."
Then have a top-quality Sneakoscope hanging there to help detect any other underhanded business, like a guy under an invisibility cloak holding a wand to the back of your father's head. While a Dark Arts Detector will likely tell you if there are other things that might be a danger to you- thing like zombies, which have no minds, thus feel no malice to show up in a Foe Glass, and can't feel sneaky either to show up on the Sneakoscope.
Build all these devices right into the doorframe where you basically MUST look at them in order to open the inner door. If any of them give off warnings, trigger off something to knock out those in the entryway, so you could investigate at your leisure.
But the overarching thought was: if your alarms showed them as an enemy, Don't Let Them In!
You had to stop both approaches. Lacking easy means of tricking an entry, they'd try to blast their way in. If blasting was too difficult, they'd try and trick their way in. It was like making a bowl to hold water, if there was any gap at all that was where they'd go through. So you had to defend against it all or you weren't safe.
Then, for cases where everything went FUBAR, have a final redoubt ready, a double-Fidelius covered survival shelter in the sub-basement. Make it so each parent held one secret, so no one person could give away all of the key. Then have them swear Unbreakable Vows not to tell the secrets under duress, or to any hostile party.
If your enemies were going to kill you, at least make them work for it.
I I I
Most of these tools exist in the original series. In fact, virtually all of them. I just arranged them in a "Gosh, you know this thing that shows the face of your nearest enemy? Why don't they use that to, like, guard their homes? Because that WOULD stop Imperioused moles and polyjuiced impostors."
And the rest kind of grew from there.