[it's jarring to hear billy this upset, and it makes tommy just want to hold him tighter, reassure him that everything's going to work out in the end, because he's going to make it work out.]

It's OK, Billy. It's not your fault I got nabbed, I ran in without much of a plan - y'know, like I always do. [He laughs quietly.] I've never been the planning guy. I'm the "run in and punch things fast" guy.

[the second part of that apology sobers tommy instantly.]

You weren't bugging me, dude. I mean, it was a little much living with you and your parents and your other brothers. [and teddy. but we're not gonna mention that right now.] I'm not used to having a lot of people around, y'know? I guess ... I got overwhelmed and that's why I had to bail. And ... I figured you knew how to find me if you needed me, but you had everyone else, so I guess I thought you just ... didn't need me.

[he's pretty used to that - not being needed, or wanted. but it's not fair to assign billy the same underlying motivations as his stupid parents, he can see that now.]

I won't make that mistake again. You're stuck with me.