"Imagine my surprise when I returned this evening and my house is back. Very strange. I imagine my brother didn't stop to consider the consequences of casting a Fidelius Charm on a home he wasn't actually the owner of. Even his large brain forgot that once the Secret Keeper is dead, the owner can find the structure just as easily as those who remained alive in possession of the secret. Anyone can really. Using a house that belongs to someone else and not getting their permission just negates the entire spell after the Secret Keeper is dead."