Emerson, or Jack as he prefers to be known, stands at about six-two, a formidable height on anyone. His height makes him appear a fair bit more frail than he actually is. While no bodybuilder, Jack is a member of the track team at his school, and is fairly athletic all-around, but not excessively intimidating. Rather, it's his cold-hearted stare and general lack of regard for most people that frightens most people off. His eyes are a chilly clear blue, reminiscent of the ice he seems to be all but made of. His black hair is kept long enough to get that just rolled out of bed look with little actual effort. He's generally dressed slightly punk-ish, but his clothes are all quite expensive, belying his family's prestige.
Jack generally remains aloof from others at all times, choosing only to converse with the few people he considers to be worth his time. As far as school he has little problems acing just about any class he's in, given his precisely logical mind. There's a rumor going around the school that he's a certified genius, but he has thus far refused to comment on whether or not this is true. It is clear in either case that he is very clever, and also that this only contributes to his bad attitude.
Inwardly, Jack is actually a fair bit unsure of himself; he's been living in the shadow of his older sister Isabelle for most of his life, and knows that his parents regard her more highly than they do him. In this respect, the snobbery can be seen as a facade. Though his family is wealthy, he doesn't care much for any of them, preferring instead to spend his time alone or with the other three, all of whom he has taken a bit of a liking to for one reason or another, though he would not admit this out loud.
Emerson Klein was born second and final child to the wealthiest family in town, and grew up quite privileged as a result. The bad attitude is in some ways an inherited superiority complex; only the rest of his family is much worse, save his uncle, who is the only relative Jack actually likes. It was this uncle who gave him the nickname, and he's used it ever since, much to the ire of his parents, who still call him "Emerson" at all times.
Jack was born with strange marks on his back, which he and his family generally refuse to discuss.
