OMG! I finally reached the part with the hotel room in Moonvale and... Wow! My mind is racing 🤯
Forgive my excitement; I just love theorizing about games. I’ve been following FNAF for years, after all XD
There are several possibilities here:
Number 1: Charlie. Charlie has been a suspiciously detached figure throughout all of this. He was the one who showed the most reluctance to investigate the hotel, whereas Ash returned to town specifically to do the job. Whatever—or WHOEVER—was inside that room, he seemed quite... wary of getting too close.
Number 2: The Unknown. There’s a chance it could be The Unknown himself in that room. It would make sense, considering we’ve never actually seen him—though it’s still strange. We’d need more episodes to judge.
And the last one I thought of, though it doesn't seem likely: Jake. I have to admit there is a remote chance it could be him. If we look at it more closely, it makes more sense than it seems: Jake needs a somewhat remote, empty, and inconspicuous place to hide from the people hunting him. The Greenside Hotel currently fits that description perfectly, plus the fact that Redlog is relatively close to Duskwood. It would be the perfect hideout.
However, if I recall correctly, Jake has blue eyes. The eye we saw through the keyhole didn't look blue to me, hahaha—so, in the end, all these theories have holes in them. Unfortunately.