BACKSTORY.
James is a seventh year Slytherin at Hogwarts. He can be rather cold and cruel; he doesn't care about anyone, with maybe a couple of exceptions. He's a Pureblood, second-born son from an elitist, well-known, wealthy family. His brother is clearly favored over him, and he hates his family, though he enjoys being able to use his family name to assert superiority. He's not a "playboy" by any means, and will not actively seek out sexual acitivity, for the most part -- though if your character offers, he certainly won't say no, either.
Though he sees himself as superior, he sees himself as superior to almost everyone, pretty much regardless of blood. He'll throw around the term 'mudblood' and whatnot without thinking anything of it, but he's not exactly the sort of elitist that most Death Eaters are. Not that he's a Death Eater, because he certainly isn't -- he's what you would call evil, but he doesn't like taking orders and serving Voldemort doesn't much interest him, though if forced he would probably take the Dark Mark. He does support the cause, sort of, and self-preservation, after all.
He can be rather moody, though it's not likely your character would notice this -- though he does have feelings, of course, he sees them as weak and doesn't allow himself to show them as much as possible. He's good at lying, and enjoys manipulation. He doesn't bother to pretend to be friends with people, though, as he sees it as a waste of his time -- especially since he's a bastard to everyone, he doesn't pick and choose. He can be rather logical, and is good at reading people.
As far as school goes, his grades are somewhat mediocre across the board. He's good at Charms and DADA, Ancient Runes and Arithmancy. He can do decently at Potions, if he ever bothers to try [which he pretty much doesn't.] He's horrible at Transfiguration and Herbology, and passing average at History of Magic and Astronomy, though he views them as useless.
These would have been his owl scores:
Ancient Runes - O
Arithmancy - E
Astronomy - A
Charms - O
DADA - E
Herbology - T
History of Magic - A
Potions - A
Transfiguration - P
Leaving him in Ancient Runes, Arithmancy, Charms, DADA, and Potions for his NEWT level courses.
His father works in the Ministry, in the Department of International Magical Cooperation, on the International Confederation of Wizards, British Seats. His brother also works in the Ministry, just starting at the Dept. Of Mysteries. His mother is a stay-at-home well-to-do sort of lady, somewhat of a "trophy wife."
Anything else you want to know? Ask.
And... BACKSTORY, GO!!