The horny personality I think is the main personality and is the one that is actually the God, it's the only one we've seen use powers. For whatever reason he has these two alters and his urge to eat people/hunger is given to the childlike one, maybe the naivete makes it easier to deal with having to eat someone. The main personality seems desperate to drive the MC away so they can get a new sacrifice, so do they NEED to eat someone every 12 years, is there a consequence if they don't? Does the Sir personality know something the others don't or was he just unilaterally selfish because he's lonely and likes this sacrifice, he's obviously no better than the other personalities cuz he's done nothing to save or stop the other sacrifices and he picks them in the first place.
We could have had the EXACT same story if she mentored him in the police academy and he just now came back into her life in the same way. Still could have had the daughter have a crush on him and she would not have partially raised him as a CHILD.