Remus

I can get behind this only because one key detail in fnaf 1 odor which is normally associated with bad smells and corpses so I believe sister location came before FNAF one it's one of the only logical things I'm thinking of it would make sense because Michael would already be dead and that's what is giving him off the smell but he probably looks normal because he's using that one thing that they had in the books The illusion discs in my opinion it seems the most logical.