My nick history would be as:
Originally Anders - because I wanted to use my name but didn't want the full version. I thought I made it up, but my gray matter must have pulled it from Norway somewhere or something, since eventually people would always ask if I was Scandinavian.
I changed it to Mental somewhere in the middle of the Aqua Demesne, I think, because people had always told me my mind was good (and my body wasn't). Ironically enough! Then I got bipolar - which still sucks, no matter what idiots like kali (sorry for the random flame, but I still think you're generally a stupid hyena when the subject comes up, and I'm gonna say something about it) like to say, so Mental wasn't good anymore.
So I took "Nev" from "Nevyn" in Katharine Kerr's Deverry cycle, from a "dweomermaster" (a mage) who commits a sin of passion that leads to his lover's suicide and his eventually living 400 years to wait for her to be born again. It's a story of pride - he's not called Nevyn at first, but takes the name "no one" (nev yn) to remind him to counteract his foolish pride.
I thought it would help with my own foolish pride, but since I'm still giving people like kali crap about their knee-jerk ideologies around my illness, obviously I haven't learned a thing.
Sorry, but you guys did ask, and my name history does tie into all that at this point.