The tattoos each mean something. His first successful job, the first time he cocked up and almost got them all killed, also the last time he cocked up and almost got them all killed. He even has one for the job where they lost Ghost, a reminder of the cost of their chosen profession, not because he missed the bastard – no he was more than happy to see the touchy, reckless man's back. But the tattoos are lessons, memories he doesn't want to forget, symbols of events and emotions and people, permanently inked into his body.
The first time he got one, after turning down the highly paid job he was offered when he graduated university, was the first time his father went from yelling to hitting, cursing his black sheep of a son who didn't 'appreciate' his privileged upbringing and Ivy League education. He got his second tattoo underneath the fingerprint bruises the man left behind, then walked away and never looked back. It took him a while, drifting aimlessly, playing music in bars and charming the good girls looking for a not-so-bad guy, before he hooked up with John and settled on a life a crime, but once he did, it gave him the same satisfied feeling that first tattoo did – like he'd finally done something that fit him and not the world's expectation of him.
G calls him Ivy League and he laughs, no trace of the bitterness he'd once carried around like a cloak. No, he's not from the streets, doesn't have the urban cred of most of his partners, but he doesn't mind. He's a criminal with class, a renaissance man with light fingers equally suited to dancing over ivory keys, controlling all the technical aspects of their operations, or pulling the trigger. He's no sheltered prep boy, or rowdy frat brother, as the backstabbing Russians soon learn – he might be pretty, but he's nobody's patsy, and he doesn't need a gun to kill you.
If they actually make this job work and all get out of it alive, he'll need more ink, something to remind him of why some things should stay past, why even for criminals, there are some rules you don't break.
And if they don't, his tattoos will still be there, a memorial to a life of choice, a life of freedom, a life played to his tune.