Dean couldn't help but look, maybe, a little bit like he was smug about it, because yeah. Castiel did have beautiful eyes. He was a handsome dude. "It's definitely better than his old angel-friend's name. Uriel." He rolled his eyes. That guy was a dumb fuck, but the difference between him and Castiel may have been what started Dean trusting him to begin with.
He laughed at the question about his seriousness, nodding his head. "Oh, yeah. He definitely can have fun, and lighten up... but he's not used to it. You know, being down on earth has changed him a lot over the last few years but he's still learning. So yeah he's serious a lot of the time."