Personality
If Topher were a flavour, he'd be mint chip with rainbow sprinkles in a sugar cone. That's what he says, anyway. To most everyone else he's a sociopath in a sweatervest and/or the boy-God of all things neuro. He's an über geek (to the point of tattooing "NCC1701", a Star Trek reference, on his ankle -- although unfortunately that's not on this particular body), and has a tendency to throw in (often obscure) references to popular culture that goes over most people's heads.
He is general very wordy and articulate, sometimes too much, and he usually covers everything in layers of snark. Occasionally he has to dumb things down just so other people can understand him. He can be a bit of an ass (a word which here means an insufferable narcissist) about his cleverness, and holds himself in very high regard (mostly justified), not knowing the meaning of 'modesty.' This often leads to him being quite condescending (even to his superiors, if he doesn't watch himself), which is one of the many reasons he's not good at making friends. He doesn't mind being the center of attention, but he doesn't much care what other people think of him. He fiercely independent, to the point of having quite big problems with authority.
He's curious and has a quite vivid imagination, and considers his work an art, and likes experiencing, exploring, discovering and learning new things. At least as long as he can do it from within his comfort zone. He's also very impulsive, but his decisions are usually rational, due to quick thinking. He can be very stubborn when he believes he's right, but very cautious if he's unsure, but he always deals with things analytically, ignoring emotions.
He's not good at thinking of people as, well, people, but rather as playthings or puzzles to figure out. He's a bit lacking in the empathy and morality department, and has no problem violating the rights of others, as long as he can justify it to himself, or simply ignore it completely. Occasionally he will do a good deed, fooling himself into thinking that makes everything else okay. Even Topher draws lines though, and he does have a conscience. It's just deeply buried. He also has touches of megalomania, and claims to suffer from acute agoraphobia (or at least he plans to), as well as nyctophobia. He sleeps on a cot in a computer room behind his office, and spends more or less all his time there, and doesn't much like leaving his comfortable zone.
History
Topher had a fairly normal upbringing, with fairly normal parents, in a fairly normal part of LA. He showed asperger tendencies early on, and had no actual friends, though he showed no problem with intellectual things, in fact he skipped grades several times.
He graduated from Stanford with a Masters in cognitive science when he was as young as 16, and persistently applied for a PhD-student position in the Massachusetts R Prime-Lab several times, before finally being accepted when he was 17. There is imprint wedges -- personality copies -- of him dating back as early as when he was 18. He assisted Dr Alexandra Rose in her research with developing the technology to wipe and imprint actives, and joined R-central.
When he had just turned 25, he started work at the LA Dollhouse, and continued to significantly improve upon the imprinting technology. He soon moved into the Dollhouse, sleeping on an cot in a computer room behind his office (which is essentially his living room and kitchen). For his 26th birthday, his boss allowed him to imprint a doll to be his friend, since he is so incapable of reaching out and making (and keeping) friends himself, and he's continued to imprint "Alex" every year on his birthday, so he won't be lonely.
When a technological error in the imprinting creates a monster out of the doll Alpha, several of his co-workers are killed right in front of his eyes, including the former Dr Saunders. Topher refuses to accept blame or consider why this happened, ignoring the questions of the morality of their work. He imprints the now out-of-commission doll Whiskey to be their new doctor, giving her largely the past of the real Dr Saunders. When a year or so later she finds out that she was created by Topher, she freaks out, and starts messing with Topher. She even attempts to seduce him, and when he rejects her, she gets angry and asks if that wasn't his plan all along, to win over the one person guaranteed to hate him. Topher says he never wanted her to hate him, but he knows he can never have a relationship with her either. Her reaction and eventual leaving the Dollhouse shakes Topher. He becomes more aware of the ethics of what they're doing, for example he refuses to revive a comatose serial killer, against orders.
When he realises that Sierra, a doll he believed himself to be helping by saving her from paranoid schizophrenia that was in fact drug-induced, was forced into the Dollhouse and that he's been deceived, he refuses to follow orders he thinks are wrong. Instead of sending her off to a lifetime of unhappiness with the man who put her there, Topher imprints her with her original self in the belief that she'll flee and be free. Instead she ends up killing the man in self defense, effectively putting a man's blood, as well as her guilt and pain on Topher's hands. Topher tries to help her, and he covers up the murder, with the help of Boyd. He promises her never to tell anyone, nor to give her back her memories of committing murder. He tells her that he can keep her secret, but he doesn't know if he can live with it.
A few weeks later, he has to go to DC for work related reasons, and he imprints the doll Victor with his own personality to run the programming while he's done. While at the DC Dollhouse, he meets their head programmer, Bennett, and quickly develops a crush on her, and she is equally interested. She then, however, tries to kill one of Topher's dolls, Echo, to settle a score with Echo's original personality, and Topher and the Victor version of himself manage to stop her.