The words are a balm on the part of Castiel's mind that's been knocked off balance, that's spinning at the wrong axis. Yes... yes, this is what he needs. To be reclaimed completely and utterly, remade by Sam's hands has he once remade Sam's brother, and Sam himself, too.

He makes a desperate little sound at it, because it sounds too good, too caring, to have Sam devote himself so thoroughly to taking him apart and putting him back together.

"Yes, Sam. I'm yours. I... can I request, your belt?" To tie him up with or to lay stripes across his skin with, he doesn't care. Just wants as much of Sam on his body as he can possibly get.