Sam drags his hand across Cas' chest, drawing angry red lines that disappear almost immediately. Sam is not allowed to leave marks on Castiel, it's the angel's privilege to leave his sign in form of bruises and bite marks on Sam, to show the world who is his owner.
Sam lets out long moan, fingers clenching to the point his knuckles turns white. His legs are hooked on Castiel's shoulders, while Cas pounds into him with full force, hitting his prostrate with every thrust until overstimulation brings tears to Sam's eyes. He desperately wants to come, to touch himself, but he doesn't have Cas' permission. So instead he sinks his nails into the angel's skin, because he needs something to hold on to while Cas continues to fucks his brain out.
"Cas… please, I need…" Sam tries to beg his angel but he's soon cut off by Cas' firm lips pressed to his own.
"I know exactly what you need, Sam." Castiel's voice is more rough than usually and his eyes have predatory glow.
The moves of his hips speed up, and Sam can only gasp and shut his eyes, stars exploding under his eyelids. Cas' claims his lips again, pushing his tongue in rhythm of his thrusts.
When Sam thinks he can't take it any longer, Castiel whispers "Open your eyes." and Sam obligates. Pleased with this obedience, Cas orders:
"Come for me, Sam."
and Sam does, spurting his release all across his abdomen and chest, sobbing with relief. Feeling tight hotness clenching around him, Cas follows him with groan.
After minute, he pulls his softening cock out of Sam and hugs still shivering in aftershock human close.
"You did so good, Sam." He murmurs into Sam's hair, running his hand in soothing motions across his back. "You're good boy."
Sam smiles, the warm feeling spreading from his heart, and relaxes in Castiel's hold. He feels tired but satisfied, and lets Cas lie him down and cover with blanket without protests.
"Now sleep, Sam." He hears Castiel's voice in his ear, full lips grazing his sensitive skin. And Sam, as always, does what Castiel tells him.