My theory is that Michael was really the crying child and he didn't die from the bite but got a big scar.... when he gets older his dad (Afton) gives him a job in sister location, he gets scooped by ennard and ennard goes on a killing spree ( because that is what he was made for)but then eventually gets spat out. then Michael trys to undo what ennard done a trys to free the souls... but because the souls didn't know what really happened the forced him into the spingsuit turning him into spring trap. which is why in fanf 6 springtrap says:"it may be hard to recognize, but i ashore you it's me".