Contest

Of the five of them, Hardison was the least fucked-up. Yeah, he was a criminal, and some people might say that's a little bit fucked-up right there, but they were all criminals so it didn't really count. And besides that, he seemed to be well-adjusted. The rest of them? Not so much.
He wasn't sure Sophie even knew who she was anymore, her aliases and cons bleeding together and overwriting who she really was. Whoever the real Sophie Devereaux was, she was lost in the sea of personalities she'd assumed in her life.
Nate had been normal once, a normal guy with a normal life. He only got fucked-up because his son died. If he didn't cling to his grief so tightly, letting it rule his life, he could have been a normal citizen again. But he was as fucked-up as he wanted to be.
There was something wrong with Parker, but he didn't think it was something that could be "fixed"; whatever it was, it had been there for a long time, if not her whole life.
And him. He knew they thought he wasn't too fucked-up. Maybe a little angry, but other than that normal. They probably thought Eliot Spencer was his real name, too.

Trust

Eliot didn't trust anybody anymore. Yeah, people were predictable most of the time, but most of the time didn't mean all of the time, and the difference between the two wasn't something he could ignore. When you trusted people, you got hurt, and it didn't tend to be the kind of hurt that a couple of ibuprofen could make go away.
He'd thought he'd never work with a team again. Working with a team meant trusting them, to do their jobs if nothing else, and it had a tendency to force you to get close to them. The only kind of close he wanted to get to people these days was physical- fighting and sex. Anything else was too risky. But the offer had been too good for him to refuse working with a crew for one job, and one job wasn't enough to make him let his guard down.

One job became two, then more. It was hard to see how this team could make him drop his guard. Parker was insane- completely untrustable. Sophie was a grifter- she could lie and he'd never know the difference. Nate was an honest man, and he made a point of never trusting those, especially since he'd been forcibly reminded that sometimes they weren't as honest as they seemed. The drinking only made it worse. Hardison was probably the most trustworthy of all of them, and who knew what he did with those computers? Why would he ever trust people like those four? Even a citizen would know not to trust them.

His distrust slipped away so silently that he never noticed it leaving until it was too late. First it was trusting them on the job, to work together and get them all out and not just themselves. Hardison might snoop (Eliot had no proof, but it's what he would do if he was a hacker), but whatever he found out he kept to himself, and what could he find out about Eliot online, anyway? Parker was crazy, but at least her unpredictability was predictable; she didn't lull him into a sense of false security. Nate and Sophie at least seemed to be on the same side as him, and even if he kept telling himself it was stupid to trust them, he couldn't help it.

All this trust was going to come back and bite him in the ass someday, he just knew it.

Strength

Xander Harris had been driven away for (supposedly) being too weak and incapable to fight. They'd just wanted to keep him safe, and never mind that he'd proven himself time after time.

Nobody would drive Eliot Spencer away because they thought he couldn't fight. He was a retrieval specialist; his job was fighting people, people who weren't pushovers by any stretch of the imagination, and he was good at it. He wasn't an assassin. He never took jobs to kill people. But a lot of the time, he killed people anyway. It was the only way to make absolutely certain that there weren't any enemies at his back, and a lot of the time it was easier than trying to keep them alive after beating them into submission. By now, he'd killed a lot of people, and he didn't really care. Alive, dead, the only difference was that people who were dead couldn't come after him for revenge. But the only hard and fast rule he had was to kill anybody who tracked him down to take their revenge. They'd shown that they were actively coming after him; he couldn’t afford that kind of risk. He had enough threats that he didn't know were coming after him.

Maybe the strength Xander had lacked was the strength Eliot possessed in spades: the strength to kill and never look back.

Becoming Eliot Spencer (v2)

Xander had thought Buffy and Willow were over trying to make him quit Slaying, but after graduation they'd made it really fucking clear that they were grateful for his help with this one last battle (help? Who exactly planned the battle and made the bombs that killed the Mayor?), but he wasn't going to be "helping" anymore. But they could still hang out. Like he was their pet, to be taken out and played with when they felt like it but left behind whenever anything interesting was going on.

And they thought he'd come back to Sunnydale after that little speech? What did he have to come back for? There were dead-end jobs everywhere, and he sure as hell didn't have any friends to come back to. He took cash from Uncle Rory rather than the car he tried to give him, and Uncle Rory was so happy to see the last of Xander that he didn't even protest. Willow and Buffy wouldn't know he wasn't coming back for months.

Nobody wanted Xander Harris, not family, not friends, not women, so he wouldn't be Xander Harris anymore. Fake IDs were good for more than buying beer and avoiding any hacking Willow might feel tempted to do to "keep an eye on him"; they were a stepping-stone to reinventing himself. In one fell swoop he changed his name, hometown, and birthdate. Eliot Spencer might have the same body as Xander Harris, but he was a completely different person. He had the accent down; now he just had to decide everything else about himself.

It was freeing. There wasn't anybody else to tell him who he was, to try to make him act like had always acted before. He was free to be anybody he wanted to make himself. In a way it was terrifying, that first time, like homemade witness protection, but he'd always done best under pressure.

He'd thrown away all the rules of his old life. Why not throw away the laws while he was at it, and do something he was good at and could make a lot of money doing?

Becoming Eliot Spencer

If there's one thing Xander knew about the criminal underworld, it was that people who had a lot of ties to the law-abiding world didn't tend to join it. People with friends and family who followed the law and worked 9-to-5 jobs didn't just give it all up to break the law. They had reasons not to do anything too bad. No, the people who got deep into crime either had ties to criminals or didn't have close ties to anybody.

Granted, from the time Xander had first started dusting vampires, he'd been breaking the law- if nothing else, stealing that rocket launcher hadn't exactly been legal. But there had always been a line in his mind: you broke the law only as much as you had to for Slaying. Dawn stealing was wrong in a way that stealing the rocket launcher hadn't been because she hadn't been stealing for Slaying purposes.
But he'd lost his anchors to the more-or-less legal world one by one, as Sunnydale fell and after. By the time he returned to the Council after his time in Africa, he's been all but forgotten by the baby Slayers, who were worse about forcing him to stop Slaying than Buffy and Willow ever had been. Wood hadn't wanted him involved in the first place. Willow was the last of the Scoobies, her last present to him before her death his eye back. And then he was alone, kicked out of the Council and with no friends remaining alive.

He didn't legally exist outside of the Council, every form of identification he'd had lost when Sunnydale had gone down and no way to get new ones. He couldn't legally buy a drink or get a job. And he didn’t have much money to start with.

Xander stumbled his way into the underworld, using the skills he'd gained fighting vampires and demons (which were…fighting. Not much use for reading dead languages on the streets) to make enough money for his first fake ID. He went for the deluxe model, costly as all hell but the next best thing to real. Eliot Spencer was his new name; he could even do an accent well enough that people believed he was really from Kentucky.

He'd planned for that to be the end of it: no more than was absolutely necessary to survive. With his new ID he went out and got a new job…he quit after a week, returning to busting heads and working his way up the ladder. Nothing too dirty- he wasn't an assassin- but if people died when he did his job, he didn’t really care. Why should he care? He'd lost his moral compass when he'd lost the people he lived for. At least in this job he got the adrenaline rush he'd gotten addicted to.

Slowly he fleshed out Eliot Spencer as a person separate from Xander Harris. Eliot Spencer had never fought demons (okay, maybe a couple, but never on a regular basis, just when they got in his way). He was charming and Southern, kept his hair long, didn't like guns, and liked to cook. And he always worked alone. He wouldn't allow himself to get attached to anybody else. That rule came along after Aimee-

It was a role, like any of the others he played to get his job done. Maybe more fleshed out than the rest, but still, it was a role, something to keep him insulated from the life he led.