Those words throw him off. He wasn't expecting it, not even a little, and it's awkward, but... he can't deny it's kind of nice to hear, either. He doesn't really have much outside this place, only barely better than what's (not) waiting for Mick on the other side of this detention center sentence. Lisa and his grandpa are all he's got, and Pops won't be around much longer. Leonard sees it when he visits, and in the way even those have gotten fewer even in the last few months. He just can't make it out as much, but he writes. That's enough, at least.

But Mick.
That's different.
He's not family.He has no reason, by blood or otherwise, to be bound to anything even vaguely shaped like loyalty to Leonard. But he is. And he cares. And it means more than Leonard knows how to put in words.

"Well...you know..." He starts, fidgeting a little with the blanket draped lazily across him. "feeling's mutual." He chances a glance over at him to gauge the reaction that statement might earn him.