I have a theory about FNAF, which makes sense at least to me. In the first FNAF you play as night guard and four different (or five if you count in Golden Freddy) animatronics possessed by dead children are coming after you and try to kill you, right? Apparently a murderer stole a Freddy Fazbear suit, lured and killed five children. In FNAF 2, I think the animatronics are not yet possessed and the murders haven't happened yet (so it's a prequel to the first game). When you get the paycheck after you've beaten the night 5, it says the date is 11-12-1987.
The guy on the phone says that the animatronics are designed to stop child molesters (I don't remember which night he says that) and I think that is why they are trying to kill the night guard in FNAF 2. I think Jeremy Fitzgerald, the guy you play as, was the one who killed those 5 children. Once in a while in the game you get weird cutscenes and I think those are the fantasies Jeremy has. However, I don't think he's insane. I think the marionette that you have to keep asleep or whatever (with the musicbox), is the thing that made Jeremy to kill the children. When the guy calls you on the sixth night, he tells you someone had stolen a Golden Freddy Fazbear suit from the pizzeria. I don't think pretty much anyone, except Jeremy, could've stolen that suit. Also the bite incident happend in 1987. It would make sense that Jeremy molested and killed those children and sometime after that he got bit by one of the animatronics. The mini games also kind of explain some things and those games could also be Jeremy's illusions that the marionette made him have. I don't know the reason he or the marionette wanted these kids to be killed, etc. It's just a theory. Also it would make so much sense that FNAF 2 is a prequel from the first game, because the phone guy got killed in the first game. And I think the phone calls you get in the first FNAF are just some trick, a tape, or something like that and that the calls repeat week after week when the night guards change. So he might not even be alive in the first game at all. Also I'm very interested about the fifth murdered child, since there are only four animatronics.
What do you think?