There's a kid I know and work with sometimes. At first I wasn't sure I liked him. He seemed quite the know-it-all, and acted sometimes like he was trying too hard to be perfect and impress. That was a year ago. Since then either he's changed some or my understanding has grown (or both).
Now he's still a know-it-all, but he really does know quite a bit. And can do a lot. But he seems a little less like he needs to show that off to everyone (although, if he thinks you need correcting in your understanding or technique, he's still more likely than not to take that responsibility on himself and correct you, complete with a thorough explanation of why). He's a little more likely to be accurate in assessing who actually needs his help and who doesn't really want it. In other words, he seems a little bit more secure in himself and his understanding of people than he was a year ago.
He really likes the concepts of leadership and serving others. He's still fairly young, but he's taking on responsibilities of people much older than himself - and doing it pretty well, I might add. He's not perfect, of course - far from it - but he does seem open to correction and teaching and will politely listen to you even if he doesn't particularly think he needs to hear it. He'll especially listen, though, if he thinks you have some expertise or knowledge that he doesn't have.
He's always one of the first to arrive, and if things need setting up or fixing you can pretty much count on him either already doing it or being ready and willing to help. He'll put in extra time if he thinks there's a need for it, too, even if it's not required of him. From what I've seen, the work he likes is where he can make things work better and where it'll help other people. (Although, again, while he's gotten a little better about it, he'll still kind of emphasize how helpful his work is.)
Some descriptive words another person gave me when I asked how they'd describe him: Confident, almost to the point of arrogance, but not quite. Cheerful (although, I would take exception to this one because I don't think he is always especially happy - not unhappy, just perhaps not as happy as some might see). Very self-motivated. Gregarious and friendly. Helpful. Mature for his age.
I have an idea, but I'd like to hear some opinions. From that short description, what type(s) do you think he might be?