The lowdown: Nate, 24, original universe, has parents, there's no Wammy's, no L and no Kira. He's a research scientist turned rockstar surgeon - the rockstar bit's 'cause he found a "cure for cancer" (well, at least that's what the public was told). Because he's of that he's REALLY FAMOUS, and because of that, his ego is as big as his paycheck. Having graduated from Stanford Med at sixteen years old, he worked as a research scientist for four years - halfway through that time, he stumbled upon a way to prevent the development of carcinoma, and thus was raised to the status of 'Best Scientist Ever.' At age twenty, he accepted a job offer as a vascular surgeon at Bellvue Hospital in New York, NY, wanting to experiment with different professions within the general field of medicine.
Nate's personal life is rather nonexistent. He lives on his own in a (rather nice) apartment in upper NYC, and has no qualms about wasting the money he's earned on toys, clothes, and computers. The only people he interacts with are patients and coworkers - however, even that seems a bit too much for him, as he's developed a pretty nasty attitude. (His general mood ranges from 'only mildly pissed' to 'incredibly, ridiculously pissed.') People who meet him for the first time expect him to be an eccentric but kindly genius, but they're always sorely mistaken about the 'kindly' bit. It's not that he dislikes people in general - he dislikes people who he considers to be stupid, and that category happens to include just about everyone.
While he does play with toys while he thinks, Nate doesn't wear the traditional white pajamas. At work he dons a pair of green scrubs and a white labcoat; in his office he goes shoeless, but outside of it he wears Nikes. The clothes he wears outside of work are pretty crazy - blazers over t-shirts are wardrobe staples, as are thigh-high riding boots and leather motorcycle jackets. This gains a lot of disapproval from the people he comes across, but it's not like he was going to be civil to them anyway.
Also, no, he really doesn't like it when he gets compared to House. He likes to think he can diagnose much quicker.