first era:
Near is, at this point, fifteen going on sixteen, and he retains his canon intelligence and love of toys. He has just become an FBI agent, and the SPK is newly formed. While Kira, L and Wammy's are still a part of his universe, his past significantly differs from canon.
Near was born with
oculocutaneous albinism, causing his hair to be white, his skin pale, and his eyes
red, although he wears grey contacts. He's five feet one inch tall, and he weighs eighty-eight pounds.
Canvey Island, England, is his birthplace. His mother left when he was four; his father became paralyzed due to an industrial accident, he was given up to an orphanage at age five. That orphanage closed down only months after Near arrived there, but that was fortunate - it caused him to be picked up by Quillish Wammy.
He was brought up at Wammy's, although he was not always #1. Mello didn't earn comparable grades, but L was fond of him -
very fond of him - and Mello always seemed like the obvious successor, thus giving Near the inferiority complex another universe's Mello might have had. Instead of hating Mello, however, Near developed a deep-set crush on him. When Near was fourteen and Mello was sixteen, Near admitted his feelings to Mello, who, thoroughly revolted, used his knowledge and intelligence to ruin Near in what he thought was a fitting punishment.
He's shy, sometimes to the point of being terrified of other people. He is interested in making friends, but he can't bring himself to regularly converse with his peers. When he's interested in someone, he discreetly follows them around in order to learn more about them. Due to his frustration concerning his social life, he throws all of his energy into work; by his reasoning, he needs to excel in something to be a worthwhile person.
Physics is his favorite academic subject, with astronomy a close second. He admires the work of M.C. Escher and often creates Escher-esque drawings, which he keeps stowed away in a box underneath his bed. His choice of fashion (the white pajamas we've all come to know and love) is based in ergonomics rather than aesthetics - he believes that white, which doesn't absorb much heat, keeps his body at a temperature optimal for working. Chess is his favorite game, but because he can't work up the nerve to ask someone to play with him, he plays against himself.
If you have any questions, fire away.
second era:
During his first stay in the mansion, he gave up his soul to
underworld_m, was returned home, lived out his life, and was then reanimated as an incubus. After a (relatively) short stay in Hell, Near was brought back to the mansion.