In-depth information is in square brackets as there is absolutely no need to know it unless you want to understand his actions. 

Name: Catseye [keeps his real name to himself for some reasons, inability of others to pronounce it correctly being one of them]

Age: around 19 [23... he looks younger than he really is]

Looks: average height, brown hair cut by shoulders, there is a scar on the right side of his face, rendering Catseye half-blind, his other eye is of deep gold colour. He wears light brown long cloak [like from old movies... or JC Denton's ;)] and owns two light (as "not heavy") swords. Under cloak wears dark clothing and a small sack attached to his belt.
[His ears are a bit pointed - but unlike elven ears are - and masked with his hair. In rare occasions when he laughs loudly, you can see that his fangs are longer than human's - not much longer though. Cloak is a bit baggy, to make Catseye look tougher than he really is - he's somewhat weaker than an average swordsman or mercenary. The two swords are, of course, twin katanas, but made a bit lighter to make it easier to use them. The sack is infused with compression magic and can fit more stuff than an average backpack.]

Mind: Usually he speaks little but when he's in mood, he just can't keep his mouth shut. Still has a strong sense of humour, especially black. Catseye has a strange (probably magic) device to play songs but very few like "his" music. He's usually friendly towards *every* race, including most so-called monsters - he has some friends among lycanthropes an predatory cats - with three major exceptions: undead (he hates them), humans and elves ("just" dislikes and travels with them only when he really has to). He tries to stay calm at all times because when he's angered it's a bit like a berserk rage - one side must eventually drop. Keeps away from alcohol. Due to his solitary nature, Catseye never aligns with one side for long.
[He is also a quick learner. About the music - he calls his music "electronic" and "scene". Odd indeed. As for the second part, Catseye believes that if you really try, you'll see that no living being deserves to be killed just because it looks different. Undead obiously do not meet the "living" requirement. As for his dislike towards humans/elves - he simply has almost no reasons to like them and quite a few reasons to hate... Catseye is a very nostalgic guy at heart but hides his feelings from strangers]

Abilities: When fighting with his swords, Catseye relies on speed and tricks rather than power. Sometimes he uses magic to help himself, harnessing the power of fire, ice and telekinesis. Never uses the magic for a prolonged time though. He can also heal minor wounds and - partially - serious ones. In combat he tires fast but up to now it was more than enough to deal with his enemies (or run away). He once made a mini bolt thrower but it isn't too useful in most combat situations. Catseye is of very strong will and can take much more wounds than you could judge from his small frame.
[I realize that this may look ninja-ish now, but it's purely coincidental. His magic abilities kick in randomly and are unreliable. He can also fight hand-to-hand when forced to.]

Story: Catseye rarely reveals his story. Five years ago he was captured by a group of (probably...) renegade elven mages. They were performing experiments on him and other unlucky beings. In course of these experiments, he was changed physically. One night he managed to escape somehow. Few days later he found out that he can use magic. He's travelling ever since, doing various jobs. In one human village he got into big trouble because people have mistaken him for a demon [the one who started all this mess simply didn't want to pay for the job]. It is there that Catseye lost his right eye.
[He's an alien, but from an earthlike world (the word "parallel" springs to mind). While travelling through a forest he found some stone ruins. Next thing he can remember is being a captive. He didn't escape by himself - a bunch of werewolves (old "guinea pigs") invaded the place where he was held. He spent some time with them and then left on his own. Never found a way to return to his homeworld and simply doesn't want to.]

Yeah, a lot of things is unsure about him. It's because even Catseye himself doesn't know everything and he never bothered to find an oracle to get all the answers.