Cas's lips are parted, his breaths sharp and quick as if pained, his eyes pen but unfocused, unseeing, as Dean slides a third finger inside. The angel moans, thrusting his hips, trying to get Dean to hit that spot again, but Dean likes the sight Cas makes, likes the idea of an angel bound in his bed at his mercy.

Dean's fallen prey to all of the seven sins, but Lust is his favorite by far and it's only fitting that if he has to suffer it, the angel should too.

"Dean. . ." Cas whimpers for him, for the release that's been eluding him for hours, for anything and the human grins. A grin that would put the devil to shame.

He pulls his fingers out and slicks himself up before sliding inside, trying to focus on not coming rather than Cas's virgin body beneath him. Dean wraps his fingers in the angel's hair, angles his head just right and presses a kiss to parted lips, taking advantage of the angel's daze to sweep his tongue inside.

He thrusts in again as Cas screams and moans his pleasure and Dean decides then and there that Cas is his. He'll brand his name on the angel's body with every kiss, with every bite, with every whispered apology because even though Lust is his favorite sin, Greed has always had a special place in his heart. Right beside Cas.

And he knows that Heaven and God and the angels won't like it. He doesn't care. He'll find a way to keep Cas with him, to make Cas his, even if the angel has to fall.

Even if Dean has to rip the wings off himself.

Cas comes, his first orgasm in his immortal life, and Dean follows, closing his eyes as he wonders when he became a monster. Behind his closed eyes, Dean can't see the look of adoration the angel has on his face and he doesn't realize that if he wanted Cas to fall, all he had to do was ask.