Petyr has Dissociative Identity Disorder, or DID. It started manifesting after he nearly died in a "duel" for a friend's honor. Now....well, it's very much like talking to very different people if you catch Petyr at different times. Because it's not just Petyr in there anymore.
Petyr is the host, far more vulnerable than some of the other personalities. He's subdued yet mischievous, and too clever for his own good. Male, straight, age lines up with biological timeline (32 at the time of plot).
Littlefinger is one of the most manifested personalities, and is by far the most aggressive, displaying the least amount of memory loss when he surfaces. He's ruthless, scheming, and wants more than anything to escape the captivity. Male, asexual aromantic, 32.
CleanHands tends to manifest after Littlefinger tries something. She wants nothing more than to keep all blame as far away from her as possible. She shows signs of OCD, and can often be heard murmuring 'clean hands, clean heart.' Female, asexual aromantic, 18.
NewStart is, to put it bluntly, a disobedient child. She is always hopeful that things will get better, but that's just about the only positive thing that can be said for her. She refuses orders and has issues with authority. Music can calm her down sometimes, though. Female, straight, 6
Jules is docile, the personality the doctors most want to see. Of course, this comes with a whole different set of problems--for instance the fact that, with such passivity comes a far greater range of memory loss than more dominant personalities like Littlefinger or CleanHands. Male, gay, 27
These are all the personalities that have manifested as of yet. WIth new situations, more may surface.