Funny story, I have an AU where Crying Child/Evan is possessing BonBon (based on that one Midnight Motorist theory FuhNaff made that no one liked, so it's kinda meant to make no sense). Evan has more control over BonBon than Elizabeth does over Circus Baby so he ditched Mike's organless body early upon realizing that this was his brother, basically through a few peeks at the house looking familiar and putting the pieces together.
This is basically how that would go
