"How come?" He was honestly curious, and although he knew talking was definitely not one of Costigan's strong points, he still wanted to encourage him to open up a little more.

If actually talking about issues and how and why he felt crappy about certain things didn't work out, he'd try to get the conversation into a territory that was less personal. Costigan had been right when they'd first talked about this - Dick didn't know a lot about him outside of his file and the stuff they'd done together on the Barge, and he wanted that to change, actually get to know his inmate better.