Maybe, he is spomething like The Real Fredbear from DSaF-a litteral manifestation and sentient embodiment of children's happiness, who was created out of pure joy, good feelings and memories of the kids that visited the original diner, and took form of/possessed the actual simptronic Abe from that place, who was the main mascot and kids' favourite. He is like an opposite of Mr. Burns/Suitcage, who is like an embodiment of everything bad this brand went, and pure agony and fear of children that were kidnapped and brutally killed by Bob, who wore that suit. Maybe that is the reason why he is more sentient and sane than EVEN Nedly, who is also the most sane and intellegent child soul in the place-because even despite it, Nedly still just......a little infantile kid......yeah, smart, yeah, powerfull.....but still kid. Abe is more like an actual grandpa to these souls