"What the hell are you doing here?" Cold green eyes look up across the library, and Castiel feels his mouth go dry, his stomach twisting as they lock onto his. There's something frightening, something… alien along with the familiar in Dean's gaze. His mouth is drawn into a hard line, no trace visible of the warmth that used to touch his face, the light in his eyes when he'd see that Castiel was there.

"I told you not to come around until you had a lead on Metatron. Do you?"

Dean's voice is hard and biting, and it almost makes Castiel flinch – but he holds Dean's gaze, makes himself take a step closer. After all, he's here because of what he discovered the last time they met – here to make sure that Dean is all right. And he can't do that from across the room, no matter how unsettling he finds that evil Mark branded into Dean's arm – or the chilling hostility he sees in his lover's eyes.

"No," he admits quietly, taking another step toward Dean, but unable to bring himself to go any farther than that. "That's… not why I'm here."

Dean's jaw tightens for a moment, his shoulders squaring. His gaze is piercing as he focuses intently on Castiel – and then the corner of his mouth turns up slightly, understanding dawning in his eyes.

"Oh," he says softly, and the low rumble of it goes straight through Castiel, touching parts of him that are left more awake, more alive with every tattered shred of stolen grace that fades away from him. "So it's something else you've come for, then."

There's something predatory in Dean's slow advance as he moves around the table and toward Castiel, and Castiel finds himself wanting to retreat, to back away – but he doesn't. He manages, barely, to hold his ground, as Dean closes the distance between them. There's an unholy light in Dean's eyes, darkened with arousal as they are, when he reaches Castiel. Dean gives him a slow, lascivious once-over before looking into his eyes again… smiling.

Castiel shivers, breaks the eye contact while he still has some semblance of control over his own reactions. "No," he says softly. "That's… not why I'm…"

The words break off abruptly when Dean surges forward, pushing Castiel stumbling back the few steps to the wall behind him. The impact drives most of the breath from his lungs, and then Dean's lips are on his, sucking what's left of it from Castiel's mouth as strong, rough hands fist in the collar of his coat and shove him back against the wall. Castiel's own hands rise to push him away, but a low, warning sound – animalistic, almost a growl – escapes Dean's throat, his hands only tightening… and Castiel lets himself surrender.

He's kissing back, trying to give as good as he gets, but Dean easily maintains control of the kiss, plundering Cas's mouth with tongue and teeth, his unyielding fist in Cas's hair not allowing any retreat. In another time, what feels like a lifetime ago, the human hunter wouldn't have been able to overpower him. Castiel isn't used to not having the advantage – but he doesn't have it, here. His fading grace has left him only a little more than human, and the Mark of Cain…

Well. Dean's a little more than human himself, these days.

Or… a little less?

Cas can't really tell, and he finds it a little exciting and a little terrifying all at once – the knowledge that he can't break Dean's hold… the way Dean smiles against his mouth when he tries, a low, rumbling chuckle escaping his lips, pleased with his own power. A shiver runs through Castiel's body as Dean's hand slides down to the small of his back, pulling him in close and a little off balance… and Castiel struggles to remember why he came here in the first place.

"Dean," Cas breathes out the moment his mouth is free, eyes closed and breath labored. "Dean, this isn't… I'm not…"

"Shut up," Dean growls.

Cas gasps as Dean effortlessly lifts him, one powerful arm under his thighs to hold him up as Dean turns and carries him the few steps to the library table, where he lets his arm slide up under Cas's coat, firm pressure against his back as he sets Cas down on the table. It's shocking, and more than a little alarming, how easily Dean can maneuver him now, with the added strength the Mark has given him.

Dean's thumb slides along his jaw, forcefully pushing his head back as Dean's lips fall to his throat, and Castiel shivers as Dean's teeth scrape against the sensitive skin there, the sting followed by the wet heat of Dean's lips and tongue sending his nerve endings firing a confusing mixture of pleasure-pain signals to his brain. Dean pulls back, and Cas finds himself leaning forward with an embarrassing little whimper, aching for the lost contact.

But Dean pushes him back, hard, before grabbing fistfuls of the fabric – far too much fabric – that still covers Castiel's body. Dean's hands are insistent, demanding as they yank both trench coat and suit coat back off of Cas's shoulders, but not all the way off.

Dean gathers the fabric in one hand so that it goes taut around Castiel's arms, trapping them behind his back. Cas's eyes are closed, but he feels Dean's hand, incongruously gentle against his cheek, his chin, tilting his head back and silently commanding his attention – so Cas opens his eyes, his vision a little hazy but slowly coming into focus on the knowing smile on Dean's lips, the predatory light in his eyes. He holds Cas's gaze, leaning in close, moving to stand between Cas's parted legs as he twists the fabric into a knot behind Cas, tugging on it until Cas falls onto his back on the table, the coarse, twisted fabric of his coats both binding and cushioning his pinned wrists.

"Dean," Cas tries again, his heart hammering in his chest, even as heat pools low in his stomach at the sensation of being restrained. By Dean. "We can't… I didn't come here for…"

Dean grabs Cas's hair again, pulling his head back and exposing his throat, and it's sheer instinct – a frightening instinct – that makes Cas immediately go silent, still and submissive.

"Don't tell me you don't want this, angel."

Dean's voice is low, warning and enticing at the same time, as his free hand slides between them to cup the bulge in the front of Castiel's slacks. Cas lets out a stuttering gasp, as Dean puts one knee up on the table between his legs, climbing up onto it, bracing himself on one hand next to Cas's head.

Cas's hands are already tingling behind him, and the position isn't exactly comfortable – but Dean's hand is stroking him roughly, the slide of the fabric against his swiftly rising erection making him squirm under the touch – though he isn't sure whether he's trying to pull away, or to push up more fully into Dean's hand.

"S-Sam," Cas thinks to gasp out. "W-where's… where's Sam? He could…"

"Asleep," Dean replies, his thumb curving under the head of Cas's erection through his pants and making brilliant sparks of light form behind Cas's closed eyelids. "Don't worry so much."

"We might…" Cas's words break off in a choked little cry as Dean squeezes just right, before reaching for the zipper of Cas's slacks. "… wake him… Dean…"

Dean backs up onto his knees again, yanking Cas up by a handful of his hair, and Cas hisses with the pulling pain of it – even as his cock twitches in response to the sensation. Dean laughs softly, and Castiel knows he felt the confusing reaction. Dean pulls Cas's head up to speak close to his ear, as he slides Cas's zipper down and slips his hand inside.

"Then I guess I'll just have to keep you quiet, won't I?"

Dean's hand slides around to cover Cas's mouth and turn his head to the side, his teeth teasing at the arch of Cas's neck, and Cas lets out a strangled whimper. The muffled sound of it against the firm pressure of Dean's hand – the knowledge that if he tried to cry out, he couldn't be heard – only makes him harder.

Dean doesn't take his mouth from Cas's neck as he lowers him back own onto the table with surprisingly gentleness. But his voice is a warning growl when he puts his lips to Cas's ear and orders, "Don't. Move."

Dean rises up onto his knees, and Castiel's body trembles, feeling cold and exposed – even before Dean puts his hands at Cas's hips, tugging his pants and boxers down to just above his knees. Dean presses his own knee down between Cas's legs, pressing the fabric down against the table and pulling it taut around his thighs. Cas tries to move, but finds that he's been rendered immobile, held down against the table, bound by his own clothing… as helpless as a pinned butterfly.

Dean's order is almost laughable now. His arms bound behind him, his legs pinned under Dean's weight – Cas couldn't move if he tried. His heart races with mounting panic, and he tries to sit up, struggling against the tangle of fabric around his arms.

Dean's response is immediate and emphatic, one strong hand gripping the side of Cas's neck and slamming him back down on the table, hard enough to drive his own fists into the small of his back and knock the breath from his body. Or maybe that's not the reason Cas can't draw breath. Maybe it's Dean's thumb, pressing insistently into the hollow of his throat as Dean bends down over him, eyes dark with lust, mouth tight with anger as he yanks Cas's head back and snarls out a warning that sends a shiver down Cas's spine.

"I said… don't move."

Castiel goes obediently still, breathing out Dean's name like a prayer. "Dean… Dean, please…"

But then Dean's hand is on his cock again, callused fingers just a little too rough, a little too tight – and Castiel can't think to form words anymore.

He shudders at the brush of heat against his ear as Dean leans in to whisper, "Please what, Cas? Huh? What do you want?"

But the electric sparks shooting up his spine with every stroke of Dean's sure, expert hand drives any verbal response from Cas's lips, leaves him with nothing more than a helpless, pleading whimper between desperate, hitching breaths. Dean laughs softly, the hand in Cas's hair gentling while his other hand picks up a steady rhythm, driving Cas right to the edge.

His body feels like it's shaking apart, and he writhes under Dean's hand, unable to help himself despite Dean's orders. Thankfully, Dean seems to understand that it's beyond his control at this point. He doesn't retaliate, just mutters a gruff, "Quiet," against Cas's mouth before kissing him, swallowing the broken, stuttering moans and half-formed words that escape his lips. He pulls back at last to allow Cas to draw breath, scraping his teeth just a little too hard against the line of Cas's jaw – and Cas is gone, his release tearing through him as Dean presses a hand down across his mouth again to muffle the sharp cry that escapes his lips.

He's gasping, shaking, as Dean lets go of him, backing off onto one knee and looking down at him with a smirk that makes him suddenly feel small and vulnerable and exposed. He struggles to right himself, feeling strangely more humiliated when Dean just watches him with obvious amusement, making no offer of assistance. Without the pressure of Dean's weight on his half-removed slacks, it's easy for Cas to get to his knees – and then, easy to shrug off the coats that tangle around his arms.

"Dean," he tries, his voice hoarse and broken in a way he's not used to hearing it, as he reaches out a trembling hand to rest on Dean's still jean-clad thigh. "I-I could…"

And his voice trails off, because it's then that Cas notices that throughout this whole encounter – Dean has remained fully clothed. He watches Cas with cold, contemptuous eyes. He looks composed, calmer now in his triumph.

He's not even hard.

He brushes off Castiel's hand with a sneer as he easily scoots off the table and gets to his feet.

"No, thanks," he scoffs, giving Cas one last derisive look-over before stalking away without a backwards glance.

Castiel feels the heat of humiliation color his face, as he looks down to take in what Dean saw – his human body, weak and useless in the light of his fading grace, half-exposed, sweat-damp and defiled, his own come drying on the untucked hem of his white shirt, and the top of his pants. He feels insulted and degraded, used… except… Dean didn't even want to use him.

Sam said on the phone that Dean hasn't been eating or sleeping well – and now it seems that he no longer takes pleasure in sex, either, beyond how he can use it for purposes of humiliation, or a demonstration of his power.

It's the answer he came for – but it leaves Castiel feeling cold and forsaken and wishing he hadn't sought such an answer at all.

Awkwardly, feeling stiff and bruised and fragile, Castiel climbs off the table and gets to his feet, then begins putting himself to rights, buttoning his shirt where Dean had torn it open, fastening his slacks and rubbing with some embarrassment at the stains that won't quite rub out.

He doesn't want Sam to see him like this – and he has to talk to Sam, right away.

It's worse than they thought; he knows that now. There's little left of warmth, or love, or affection, in the man who's the most important person in both of their lives. He's grown cold and threatening, brutal and sadistic. And worst of all… the thing that sends a cold tingle down Castiel's spine, and leaves him feeling empty and scared and fighting off a creeping sense of despair… is the scorch of hellfire that still lingers at the back of his throat, the taste of sulfur when he licks his dry, trembling lips.

He and Sam have matters of grave importance to discuss. Together, they need to find a way to raise the Righteous Man they love from perdition once again.

Castiel only hopes that by the time they find a way, this time – there's anything left of Dean Winchester to be saved.