"Your Grace is diminishing fast, little brother."
For the first time in what must be hours, Castiel feels something other than the chill of Bobby Singer's scrap yard — but before he can pin down the voice, or why the sudden warmth at his back feels so wrong, there's the rushing sound of wings and the scenery around him changes. His clothes disappear as he tries to take in the change of place, the sudden presence of pillows, sofas, and a fireplace where there'd been broken down cars. And as he's jerked into an embrace, as he hears the mutterings in Enochian — so beautiful... those humans don't understand us and they never can... why do you try so hard to fight it? — as he feels the teeth grazing over the back of his neck, Castiel's urge to resist falls apart.
"Lucifer," he hisses. He hates the way that his knees quiver, and their refusal to support his weight, and how they send him slumping backwards, so that his brother's arms can tighten around his shoulders.
The Morningstar presses his lips into the back of Castiel's neck; they curl into a smile, and then his teeth gnash at Castiel's skin again. "I know your name too, brother," he says. "Just as you know that it's pointless to try and fight me."
His hold is warmer than it has any right to be, and his voice blazes across Castiel's skin as he keeps whispering the syllables in their native tongue — each one hits Castiel's muscles right on some spot of tension, then Lucifer follows it with a nip here, a bite there, the occasional breach of skin that sends heat and relief blooming throughout Castiel's body. When he does draw blood, Lucifer lingers on the spot, sucking on it, working it over with his lips and tongue. He gnaws at the spots, leaving a trail of violent red marks in constellations on Castiel's back
And this isn't right, Castiel tries to remind himself as Lucifer goes lower and lower, ghosting one hands over the slender muscles of Castiel's chest, rubbing the other's fingers over Castiel's bruises until they cool to purplish hues — there shouldn't be any comfort or heat in this hold — distance from their Father such as Lucifer's makes things grow colder. Rumors say his cage is frozen over, like it's carved out of a glacier — but each exhalation hits Castiel's skin and makes his knees wobble, whether or not Lucifer's breath comes with words; every brush of lips against spine or shoulder-blades gets Castiel to tremble. Each time Lucifer nibbles at him, Castiel feels like fireworks are going off, reaching down to his bones and heating his entire being, physical and Grace and all...
Lucifer's tongue flicks up Castiel's spine; he shivers under the contact. "This will be so much easier when you admit that you want it, Castiel."
It should feel wronger, Castiel thinks, as he lets Lucifer bring him to his knees, then coax him onto his back. His passive acceptance of the Morningstar's lips against his own should trouble him more, but instead, he feels his stomach churning the way he doesn't fully understand, the way that it only does around Dean. Lucifer takes Castiel's lips upside-down, keeping one hand on his younger brother's cheek, and Castiel doesn't understand how his own mouth moves against Lucifer's how it does. Even without that comprehension, he still loses himself in the kiss, leaning headlong into it and biting back until bruises cover his lips and Lucifer's alike. His Grace pushes against his chest, yearning to get elsewhere, to commune fully with the Morningstar's; keeping it contained takes concentration — Castiel bites on his own lower lip and screws up his face, trying to remember who — no, what — his brother is. He succeeds, and it doesn't matter; his dick still twitches, and gets fully hard Lucifer's teeth dig into Castiel's lower lip.
"I know that you were lying to the Winchesters back there, Castiel," he whispers against Castiel's mouth. "I know that hunger was yours, not Jimmy Novak's."
Castiel knots his fingers up in Lucifer's hair and tugs with the intent to take it out. Lucifer just smirks. He slithers down the length of Castiel's body, dragging out more nips and leaving more red marks all over the other angel — he places a triad around each nipple, and a twin lines down Castiel's stomach; he draws blood as he gets closer to the cock. "Your poor vessel, brother... Can't you feel how neglected you've left him? If it hadn't been for Famine's interference, he might have died of starvation when you left him."
Pausing, Lucifer teases his fingers against Castiel's prick; he lets one drift up and down its length, almost touching the sensitive skin, almost caressing the head, but just missing it, even when Castiel bucks his hips toward his brother's hand, trying to get the contact Lucifer's denying him. "And naturally, his hunger isn't the only part of him you've ignored." Lucifer tut-tuts at this, and promises to be gentle while he fixes this. As he takes Castiel's girth into his mouth, lets his teeth creep back up the shaft's underside, he doesn't notice how Castiel moans beneath him or how Castiel's fingers clench around his ankles.
"You should show me some respect," Castiel whispers. He throws his brother off of him, onto his back, and leaps to pin Lucifer down before he can react. This makes a glint flash across Lucifer's eyes, some smugness that Castiel tries to kiss out of the Morningstar, biting and sucking at his lips as if trying to remove some poison — Lucifer only chuckles, and shakes his head. "I'm not some child you can toy with, Satan," Castiel says. "I have a team standing with me, and we won't let you win."
Lucifer's smile has a poisonous condescension to it. "Yes, and it's quite a formidable team, little brother. A cripple, my true vessel, and a self-loathing drop-out with a martyr complex. Oh — and Crowley, who has, I believe, gone missing ever since those shenanigans in Carthage." He leans up into Castiel's lips, sucks on the lower one, and hisses, "I'm shivering."
Castiel could argue this, but he can't stay here. He needs to get back to Sam and Dean, and debate would give his brother too much of a chance to distract him, to keep him — but he can't just leave their words at that. Before he spreads his wings and makes his exit, Castiel steals another kiss, letting himself savor every motion of their mouths, every collision of their tongues, and every gnashing of his teeth or his brother's. For good measure, he makes sure that he leaves Lucifer's lips bleeding.