Oooh ooohhh wait this theory could work, maybe they were all different people before too and the body originally belonged to the 4th personality and all the other guys sacrificed their bodies to keep him trapped in his own so he couldn’t hurt as many people, but they aren’t strong enough to hold him back for good hence why they sacrifice people every once in a while!!!
I would say they are all gods, in mythology characters are gods of stuff or ideas (don’t quote me if that’s wrong), so my guess is the supposed 4th god is a snake god of something that eats people, jerk mugo (if he’s the dubious one, I mentioned in another post he could be the benevolent since I don’t really trust glasses mugo)could be a god of lust or desire, monster mugo could be a god of savageness or something and might have the form of a child, glasses mugo if he’s actually benevolent would be a god of something good and have the form of an older person.
If that doesn’t make sense I was rushing and I don’t really know either but basically I think they are 3 different gods with different forms who all work to suppress a certain part of snake mugo (4th personality?) but it’s getting harder for them to control him since they have yet to sacrifice someone. I would say monster mugo is the most affected since like I said he seems childlike and children are generally not as mentally strong or something idk ( ̄∇ ̄")
Baby is falling for this Mugo too. He's not spending time with the other two so Jerk Mugo seems to be the ML rn and he seems to be more tame (popular) now. I don't believe that any of the personalities are sus or bad, they just have a duty to perfom. Like working together to keep the forth personality (theory) at bay. That's why Sir Mugo (Glasses Mugo) was telling Lord Mugo (Jerk Mugo) to find another sacrifice for the Monster Mugo (4th), not the Childlike Mugo who just seems to be manifesting the Monster's hunger and that hunger (for sacrifice) it's gonna affect all of them in different ways.