Dean frowned a little, because it wasn't even just about bleeding for the Winchesters, it was about the fact that Castiel was a Winchester in nature even if not name, and that meant Dean was possessive, it meant Dean expected Castiel to run away and leave him. It was only now Dean was starting to truly believe Sam was staying around for the long haul, because they seemed to always keep losing each other, the three of them.
"Whichever kind of happy you think is best for you, Cas. It's gonna hurt like a son of a bitch when we all go home and the people we're close to here don't come with us, so you gotta figure out what's best for you." He didn't want to think about the day they were all told they could go home but they had to say goodbye to people.
Dean felt his heart tighten up a little, his throat clench, and he didn't quite know what to say. He fussed and he whined and he was awkward about personal space with the angel, but he was the one person besides Sam that Dean really felt closest to. It was difficult not to just hug him, but he reached to slide his hand over the back of Castiel's hand on his shoulder. "You... I... the same, okay? You need someone, I'm your man, alright?"
Nodding a bit to the angel, Dean gave him a firm pat on the chest. "You figure out what you want. Me and Sam, we'll always be around. Just come when you've got things down."