List ten traits that, put together, identify you uniquely. Don't use inherent physical traits (brown hair, blue eyes) unless they're really distinctive (six fingers, born without a spleen). Also, try to avoid "things that I like" - these are the top ten traits that, if anybody else had every single one of them, would make them your twin.
I am a packrat. I save everything. I have two old ponytails, old concert tickets, beat up 1960s Mad magazines, bits of metal, random instruction booklets and computer game installs that last were used on my XT and played on the amber monitor. I am frrequently heard to wail "But what if I need it!" when forced to throw somerthing out.
I do a lot of things, but none of them with full commitment. I make chainmail, but not very often. I draw, but not professional quality. I study martial arts, but I am neither a badass nor a zen master. I am polyamorous, but too antisocial to manage secondary relationships. I'm a goth, but I don't go to clubs very often, nor am I really connected to the scene. I read comics, but neither keep up with the big superheroes, nor enjoy the deep indie comics. I'm bi, but have never slept with a man. I'm a programmer, but I've never written my own compiler. I am on the fringes of countless scenes, and an indsider in none.
I'm quiet. I spend most conversations just sitting and nodding, making the very occasional comment.
I'm fairly closed, emotionally. I don't talk about how I feel, and I don't let people in. This overlaps with #2 and #3. I don't give anything away, and always wait for someone else to make the first move. If you're interested in me romantically, and waiting for me to make the first move, you will have a very long wait.
I'm paranoid. I check shadows to see if I'm being followed too closely, I check reflections to see if there's someone waiting around the corner for me. When I get really keyed up, I even make a point of checking up in case an attacker might be coming from that direction. I'll back away from helping someone because I can't think of a way to do so that wouldn't open me up to a potential attack. I probably could have started dating almost ten years earlier, but I assumed that the girls flirting with me were doing so as part of some kind of nasty joke. I am convinced that most of the world is out to do me harm.
I'm messy. Compulsively so. I get uncomfortable when me space is too tidy; more to the point, messiness is my way of making it "my" space. When I visit other people's places for a day or two, I will usually scatter my stuff around wherever I'm sleeping to mark my territory. I do this more or less unconsciously; it's only in the past few years that I've figured out what I'm up to.
I like to do things myself. I would rather leave a new pair of pants sitting on a table for a month waiting for me to have time to hem them myself than pay someone else to do it. I probably could have made it through my degree at Waterloo instead of dropping out if I'd gone and got help from somewhere when I was in over my head. I hate asking for help, and will spend a lot of time and energy trying to fix things myself if there's even a faint glimmer of hope that I can do it alone.
I hate phones. I don't like calling people at all. I get panic attacks when I have to call people I don't know, or where I don't know who will answer the phone. I don't like having long phone conversations. I've gotten somewhat better about this over time, but I'm very glad that more places are letting me do things online these days.
I look weird. I dress in black 98% of the time. I tweak my appearance as much as possible, changing hair colours, hair amounts, boots, makeup, when I can get away with it, boots, homemade jewelry, and also boots. The only things I'm really tied to are a) black, b) boots, and c) that it be somewhat weird in one way or another.
I tend to respond analytically rather than emotionally. If someone comes to me with a problem, I will try to solve it. This works when the problem is "why does my code not compile", less well when the problem is "why is my lover a dickhead". This is why I still classify myself as an atheist rather than a pagan; I approach the matter with logic and analysis, and can't manage to solve for "faith" or "belief". It also may be part of my confusion dealing with people, since I can't solve for humanity either. (I am a star trek computer)
bonus! I tend to be overwhelmingly negative/pessimistic, as a quick review of these ten items reveals.