She'll start with Celegorm.
Lúthien leans back on her bed, casting a quick glance at the shadowy door. Celegorm, along with that dog, has already been by for this particular evening's round of dinner and what he's pleased to consider 'courting' and she considers 'ongoing crude and vile attempts at seducing' her.
She'll start with him, when she takes her revenge. It'll be easy at first, a soft, sly smile, pretending to give in a little. Perhaps a tear or two, a sparkling glance upward. He'll think he's won, the ice maiden melting into dew-like tenderness before his very eyes.
Lúthien grasps the edge of her gown and pulls it up so she can slip her hand beneath her skirts. Meditatively, she strokes the flat of her hand over the soft hairy folds between her legs, already warm and just beginning to swell under her touch. She doesn't dip between, not yet, just considers her next steps.
She'll allow herself to be tumbled back onto the bed. Impetuous Celegorm won't bother much with foreplay or drawn-out kisses, he'll get right to it, will barely consider her arousal to be important to his pleasure. She'll give in after a little frantic squirming - perhaps plea virginity, so he'll take a little more time - and take him into her body. He'll have a moment's pure pleasure, just enough to let him relax, let him think he's hunted and conquered his prettiest prey, before she'll spring, turning from hunted to hunter.
She dips the tip of one long delicate finger between the lips of her cunt, gathering up the fluid forming there and bringing it up to her clit, slippery and salty. Her strokes are unhurried, dainty. She touches herself like a lady, no matter the violence in her thoughts.
For now they do turn violent. She lashes out with suddenly sharp nails, raking down Celegorm's face, and as he cries out in surprise, she turns them over, him still inside her, so now she's riding him and he's the one flat on his back, eyes wide, face bloody. He's half off the bed, unbalanced, unable to regain control of the situation. Her hand is quick to move to his throat, and he sees in her eyes the implacability of his Doom. She will have no mercy, she will not turn aside, not for him, not for Morgoth himself.
Her hand is moving faster now. She bites her lip, enjoying the small pain which only adds to the sensations running all through her. She's very wet now, and the sounds her fingers make are loud in the quiet room. Her breathing is under nearly perfect control, deep and calm. She won't lose control until she explodes, of that she's sure.
She presses down hard. She's still fucking him, and the look on his fair face is agony and ecstasy mingled so thoroughly that she can hardly begin to tell them apart. His mind is buzzing against hers, but for now she shuts him out. Such an unfortunate child, to contest itself so against a power it knows so little of. His face is growing red with the lack of air, and she smiles, pressing down all the harder.
//You'll be one of us//, she hears inside her mind, faint and far away, as if it is her conscience. //Kinslayer. Kinslayer.//
//Then let it be so//, she says back firmly to that small voice that is Celegorm's. He gives a great shudder at that, and she can feel his seed spurting inside her even as the light in his eyes goes out and he sinks back limply on the bed.
Flushed with triumph, she drives herself down on his hard cock one last time and comes hard, her body clenching around his dead shaft, his breath gone, his heart stopped by her hand.
Her vision goes white with savage ecstasy, fingers moving at a blur. At last her breath is ragged, trembling. She spills in great waves, shocked delight raging through her like a fire that blazes up and dies down just as quickly. Her hand falls from herself, dropping onto the bed, and for a long moment she can do nothing but gasp and stare up at the earthen ceiling, wishing desperately for the stars.
When, a little while later, Huan comes to her with her cloak in his mouth, and speaks in words to her, Lúthien drops her plans for revenge in favour of flight. She can always enact vengeance later.