Sam gave him a small smile. "Nothing," he said, honestly. "You're just going about it the wrong way."
Hopeful was, maybe, the wrong word. But Cas's viewpoint was, in a certain way, more hopeful than his own-- by contrast, Sam's realistic point of view had seemed 'negative'. It was hopeful, or optimistic, or some other word that he wasn't coming to him right now, for Cas to be living here, with Dean as a demon, and believe that everything was okay.
He shifted his weight in the chair. "Believe it or not, I'm fun. And relaxed. And hopeful. I'm going to continue being that way, because I'm going to face everything head-on, as it comes. The way I always do, for better or for worse." The wryness in his smile indicated that he was acknowledging the mistakes he'd made in Cas's timeline... in his timeline, potentially. With Cas's timeline, with Dean's, with the one he'd woken up to but not seen on television... he didn't really know what timeline was his own anymore. He was from before the timelines split, and his had diverged here now.
Sensing Cas's discomfort, he looked away, around at the kitchen. "I think I'll start with this apartment, it looks like it needs a lot of work."