The praise goes straight to Castiel's head, his heart, his cock, makes him feel dizzy and warm. He has a thing for that, and suspects Sam is well aware even if Cas has never specifically called attention to it. His whole existence was based on obeying, following, being good and falling in line, he's hard-wired to accept that as the only way he can earn love. And Sam doesn't just give his love unconditinally, no, he praises Castiel, shares his satisfaction and making Castiel feel blessed, worthy, loved.

The fallen angel needs that praise, tonight maybe more so than ever before.

The stretch of his mouth around Sam's cock is amazing, and he can hardly believe he's good enough to deserve it when all that's required of him is holding still and letting Sam fuck his mouth in slow, lazy, shallow thrusts. So Castiel moans, lets his throat vibrate ever so slightly around the leaking shaft, encouraging Sam to push in, let Castiel swallow all of him and suck on him. Every push coaxes those needy, lust-filled noises from the former angel, as if Sam fucking his mouth gives him the greatest pleasure, as if his body is receiving this blessing for the first time all over again.