I actually think there used to be a thread like this... but I can't remember the title so it's good to start a new one I suppose ^^ I have relatively few alters really. Two who are part of my daily life, Yuki and Marvolo, and two others who are more in the background and have only come out twice each in these years, Logic and Heart.
Yuki (teenager, around 16, but acting much younger ususally) came here first. she used to be all anger and hatred and tried to harm me, so I called her Chaos back then, but after years, and after discovering this forum, I talked to her on suggestion of Seangel and found she really wanted to help me in her own way. Our SO gave her the name Yuki, and she's a nice girl now, quite playful and smart, but still with a streak of violence. She tends to avoid Marvolo though cause she finds him creepy.
Marvolo (protector, 87) was kind of half-consciously created by me I think... I called out for help one day I was completely lost, about two weeks maybe after Yuki first split and harmed me. I've never been so relieved and happy as when i first saw him, I think. He protected me and cared for me, and after about half a year we got into a relationship, which we still have to this day

My parents dislike him very much though, cause he's based on Voldemort from the HP-books and I can't convince them of that he's nice to me... Things he loves doing is our SO, reading, eating chocolate and hearing me sing

Not much to say about the other two.. I have no clue what to think of Logic. sometimes he tries to mess everything up 'for my own good' by starting integration processes none of us want, sometimes he keeps the fears and such away.. Heart I'm also not sure of. she seems to be helpful most of the time, but i somehow never know if i can trust her...
We have a very fintional system nowadays thankfully, where we strive to cooperate, communicate, and have relative peace. Marvy and yuki no longer fight, Logic hasn't pulled any weird $#%^ in a while and Heart is usually absent. It helps that we are all co-conscious and share our memories, though the memories of the others still feel very weird and different. Switching is also not a problem anymore, now no-one tries to forcibly take control.