How can something involving the human soul can be affected by something as mundane as property law?
Not to mention, the house at the secret to the location of the headquarters at Num. 12 Grimauld Place was kept by Dumbledore, nothing changed about that so far.
-mo
Author's response
I've seen the Fidelius charm change hands in many ways in various fanfics.
In canon, I know the secret passed to everyone else that knew of the secret on the death of Dumbledore. If the secret was locked up so tightly in D's soul, how did it pass simply because he died? Answer, because JKR wanted it to happen that way. Realistically, it would have made more sense for things to stay exactly as they were, but with nobody else being able to learn the secret (unless there was a note written by the SK lying around somewhere)
Canon therefore shows us that it is possible for the secret keeper to change hands in at least one circumstance.
Ok, so as far as canon goes, Harry didn't become the secret keeper upon taking possession of #12.
In canon though, Harry never attended the actual will reading, and didn't sign anything in his blood, so perhaps things didn't pass as fully into his ownership as they could have?
It's possible Dumbledore just ensured that Kreacher was transferred over, and he did something to keep hold of the secret.
Sure, the transfer isn't as tidy as I'd have liked it to be, but it is still plausible, and I didn't really want the whole distraction of summoning Dumbledore via Fawkes, demanding the dismantling of the existing Fideleus and then having it recast with Harry as Secret Keeper (which was one of my other options, along with demanding a note that he could pass around.)
Cheers,
Brian