Great story so far. A refreshing change and I'm glad I found it.
It is surprising that the story is so interesting with the decided lack of main characters. I do wonder how much of this happened because of the time travel and how much just happened and we didn't know about it.
Please continue.
Author's response
Thank you! I think once I have written another 100-200k words, it will feel more like there are some main characters. Although the canon main characters will always be peripheral to the story, just as part of the rules I have set for myself to make the story interesting.
Which is original, which is because of changes: in my mind there's a little of both. Stories set in this year have to deal with some puzzles like when Quirrel's sabbatical ended, and when Charlie stopped playing quidditch (and thus leaving Oliver whining to Harry the next year about it, which fans argue about on the Internet). The time travelers will often not be in a position to know which is which either, so it will never be revealed to the reader in-story in those cases.