I'm not really sure which kind of orphan I like best; maybe I like them all. There are so many ways you can go with it. @Circular Logic was telling me about this character from Mass Effect (which I've never played) named Jack that sounds like a cool sort of take on the orphan type. Dangerous but not necessarily a villain. But I also really like the arc of a villainous orphan (metaphorical or literal) who changes after being shown a lot of compassion. I know this arc has been done in the EU, but I don't think that's a strong argument against using it in the films. I like the way @Immortiss describes a possible arc as "distrustful and selfish, but learns to be benevolent." A lot of emotional resonance there.