Bela is a tall (5'8" according to IMDb), moderately curvy brunette with light colored eyes and a permanent smirk. No, seriously, the edges of her mouth curve up, naturally and constantly. She's always well dressed and groomed, usually wearing gray or black or some combination of the two. She looks mostly to be your sort of typically posh English girl.
As for personality, well. Flat out, Bela's a bitch. She's cynical and selfish and has absolutely no qualms about her "everyone for themselves" attitude to the world. If she can see where it's a benefit to her, she'll do it. If it in any way inconveniences her, she'll try to get rid of it. She's very intelligent and an excellent sneak thief, but also very overconfident, generally expecting people to be slower and less clever than she is. She believes in the power of money, doesn't believe in being good just to be good, and thinks that people who ARE good are lying, naive, or crazy. She's not evil, she's just very, very self-centered. And, you know, a bitch.
Not a whole lot is known canonically about Bela's past, so I would prefer to keep that "shrouded in mystery" (to put it pretentiously) so as not to get TOO Jossed. If asked IC about her past, she'll give general, vague answers. Anything further is none of your business, and she won't be coy about saying so. One thing that we do know is that she's responsible for the death of a close relative, something which I'm going to play as being the trigger that lead her to be as darkly cynical about the world as she is (she states in her first episode that everyone is going to hell, anyway. She might as well enjoy the ride). While that incident most DEFINITELY falls under "things that aren't your business", Bela believes completely that she was right to do whatever it was she did, despite the fact that "you wouldn't understand. No one did." IMO, that incident is also what pushed Bela into the supernatural world.
Bela's aware of the crazy, supernatural truth of the world. She knows about spirits and curses and demons and things. She sees them entirely as a means to an end. She has a talking board (like a ouija board only not trademarked) that she uses to communicate with the spirits to get information when she needs it (and would be willing to use it to help out others, for a price). She's a sneak thief, a mercenary, and a con-woman, so she's very good at lying, pickpocketing, and negotiation (though, to some extent, at the stage I'm be bringing her in, she's still developing some of those skills). She's handled guns, but I would say has not used them extensively in the field, just yet. She's starting to build a network of contacts (mostly buyers) in the supernaturally aware community, which she's willing to put to use . . . again, for the right price. She's good at research, but often overlooks the "why"s and "how"s of a question (such as "why is the ghost ship choosing the victims it's choosing") in favor of the "what"s and "where"s that she needs to get the quick sale.
Bela's coming in pre-canon. She's been educated for the majority of her life in the English public school system (the rough equivalent of an American private school) and comes from old English money. It's been decided for her that her education would be more well-rounded and she'd stand a better chance at getting a good husband and job if she were to spend the last few years of her pre-college education in the states, especially since this would put physical distance between herself and the other people involved in that unfortunate death incident. In essence, she's being punished, banished, exiled for her part in that incident, and she's well aware of it. Besides, her focus on the supernatural world is really starting to creep people out, back home. Just what is she always doing with that talking board at all hours of the night? And who is she going out to meet with? Really, sending her away to finish her education is for the best for everyone concerned.
Bela's not above mocking, bitching, or betraying her fellow students/friends. But she's also aware that these are people she can't easily leave behind until graduation, and would prefer not to live uncomfortably with everyone around her. Also, she HATES it when people hold a grudge against her (as she tells Dean in her third canon episode). So while she'll backstab when she can turn a profit, and refuse to help when she doesn't see what's in it for her, she sees that getting along with the majority of her fellow students is in her best interest.
That doesn't mean she can't have a few friendly (and not so friendly) rivalries, but she won't go out of her way to start something, and will put her resources (money and contacts) to good use when she sees that a social bridge is in need of repair. And she has no intention of STARTING anything.
Questions?