A/N: These characters belong to the CW and, specifically, to Eric Kripke. If this had actually happened on the show, I'd have died. Enjoy!
It had taken a couple of manic bouts of paranoia (Demon? Ghost? Hallucination?) for Sam to realize that he was dreaming when he was with Jess. It didn't stop the panic, though, the clear and present unease that he felt when she'd rest her hand, careful and small, on his arm, stroking back and forth in the soothing way she'd always had. They'd sometimes sit for hours like that, Sam's eyes far away and full of things she knew not to question. It felt the same in the dreams and somehow that made it worse, made it wrong.
Of course, there were more awful things than the knowing brush of her fingers against his skin. With every breath, he could smell her, warm and clean like a summer sun shower. She'd never been silly enough for the overbearing floral perfumes the other girls seemed to bathe themselves in. The scent at the nape of her neck and sweet little curve of her belly, fresh and feminine and Jess, made him ache for her as he hadn't let himself in years. He was forced to listen to her voice, gentle no matter the words she used, as if she were easing him down, leading him into her quiet calm. It was easy to forget the things she was convincing him of when he was lost in the familiar bowed flesh of her lips around the words, something he thought he'd long forgotten.
And of course there were the times he tried not to think about. The nights when he woke up, self-hating and glazed in a sheen of sweat, the flutter of her tongue lingering in all the wrong places. At first he resisted, pressed her soft, yielding body away and begged to me left alone. But the more he believed the things she said (he couldn't run from himself any longer, not who he was or who he would be), the more he gave in until he broke, devoured and marked her, knowing she'd be perfect again the next night.
He tells himself that he knows it's not Jess. That it couldn't be. He digs up the long-suppressed image of her body, pinned and blazing, and says to himself, "She's dead." He does a few half-hearted searches on the old strain of succubi, the ones who visited your dreams to tease you and fuck you and drain you until you were half-mad and fathering a demon child. It won't happen that way, not for him, because he won't do that. He won't use this body, the hollow echo of Jess, no matter if he's only dreaming.
It isn't easy. She begs and rocks against him, slippery wet and burning up from the inside. She pleads to him, his name on her tongue again sharp like a fresh wound. It scares him every time and he's sure that each time is the one that he'll give in, push up into that tight, melting heat and give her what she's begging for.
After a while, she figures it out, panting his name between kisses, tracing it into the skin stretched taught over his collarbone. "Sam," she says, no longer pleading, "Sam, it's not her. I'm not Jessica." He knows. He knows and yet it still fucks with his head, turns his world upside down and won't let him forget. Yeah, it's not Jess, never was, but finally he lets her ride him as if she were. He almost smiles up at her , her blissed -out face and the bounce of her breasts beneath her hands, until he remembers, and when he wakes up sticky and alone, he wants nothing more than to shoot himself in the head. He doesn't sleep for days, stealing half an hour here and there when he can, careful not to sink too deep where she can find him. He thinks hard about all of the things she's told him (they're all just going to keep dying, all for him, all because of him) and wonders just exactly what he's supposed to do about it.
Demon blood or not, Sam is only human and he makes it almost two weeks before he passes out sitting up in bed. He groans at the first brush of fingertips before he registers the shape and size of the hand cupped against his face, the rough pad of the thumb tracing across his cheekbone. When he opens his eyes, he's unsurprised to find a man there, looking down at him with no malice or curiosity, only the same quiet calm Jess has worn all this time. He should push away, should fight like his instincts are screaming for, but he knows he's still dreaming the way that he knows that whoever this is, he knows them.
Tilting his head inquisitively, the man drags one finger across the crease of Sam's brow, as if bothered by the worry there. "I'm sorry. I thought Nick might make you feel less….guilty. I can be Jessica again, if you want. Whatever you need, Sam." He scrubs a hand across his own stubble as if for the first time and shivers. "I think I'm more accustomed to her by now than to this…temporary fix. It walks and talks but it's just not the one."
"Who…?" Sam trails off when the man's wandering finger drops to his lips, resting softly in the universal sign for quiet. He still needs to know, though; needs more than anything to find out who this is that wears Jess like a glove and knows him inside and out more than anyone ever has. More than Jess had, definitely, and unbelievably, more than Dean. Every second in his presence is a punch to the gut when he feels that pull of familiarity, like déjà vu but ominous, fraught with danger.
"I came here to reward you, Sam. I brought her to you again, let you have the one thing that made you feel normal. But even then you knew something was wrong, didn't you? You could feel it, that there was something more waiting. You knew she'd end up dead because of you."
"No, I-"
"I'm not talking about the dreams. I'm talking about the way you felt empty after you touched her. How she was too much and never quite enough for you. She was never meant for you, Sam. A good pawn for the plan, but she never could have completed you." The man smiles at the hot pinpricks of tears in his eyes and thumbs them away. "Too much at once?" His features soften, slip into the face he's worn for the past several weeks. "Better?"
Sam waits until he's sure he's really meant to talk again and breathes in as slowly and carefully as he can when his insides have wound themselves into knots. "I don't know who you are, but you're wrong. I loved Jess, more than anything."
"More than your brother?"
The quiet answers for him and his shoulders shake with a sob he won't release. It's too much and he still doesn't know who the fuck he's dealing with but it's so much easier to bury his face against her shoulder and hide than to think, than to try to deal with all the layers of guilt and denial he's buried everything under. She pulls him in further, breast pressed tight against his chest, nails drawing wide, tickling curves across the skin of his back as he cries.
"It's alright, Sam. You don't have to lie to me. You loved her. You wanted her to be it for you, even after she was gone." Gentle hands skim up his sides, come to rest beneath his chin, tilting his face up. "But she didn't ever really make you feel like this." She thumbs his cheek and dives into his mouth, slick and open and insistent, pulling him flush against her and then pulling some more, as if she can't get close enough, as if she wants to crawl inside. When she guides his hand up her thigh, he touches her on instinct, light, teasing touches until she whimpers into his mouth and grinds down against him and he releases her mouth and lets her push him down.
It's the same as it always is and yet so different, knowing for sure that Jess is nowhere in this body that feels so much like hers when she sinks slowly down onto his cock, hot and so tight that the pleasure is just this side of pain with its intensity. This time, she leans down and kisses him as she moves, fast and hungry and more demanding than he remembers. She mutters against his mouth, the same words over and over again, and he doesn't know what they are until she pulls back a little to ride him harder. She's thanking him, sobbing with a gratitude that doesn't fit the situation.
"For what?" he asks in a moment when the pleasure doesn't weigh so heavy on his tongue. "What'd I do?"
She opens her mouth to answer and lets out a moan instead. She's close, hovering on the edge of a pleasure that's almost brutal, and Sam remembers how Jess had liked to ride that line, to drag it out until there was nothing but the insistent throb of need pulsing through her body. He holds her hips, grinds slowly up, and repeats his question.
"For letting me out," she pants, hands leaving his body to trace her own. "I was in there so long, Sam. They locked me up and let me waste, let me suffer, and you set me free."
A wave of horror hits Sam like a rush of cold water, but she's pushed his hands away and started moving with intent, almost bouncing on his cock, and he can't stop it, can't push the warm clench of her body away as she keens and flutters around him. No, not she, it was never her, he knows now more than ever. He feels the fire start at the base of his spine, stabs up into the heat above him again and again and knows just who it is that takes him so easily but makes him feel like the one being filled.
"Please," still Jess's voice sobbing, "please Sam, you let me out, now you have to let me in. Just let me in, Sam, and I'll give you everything. You can have this, you can have it all, just tell me I can have you."
The world around him blinks out for a moment and it's like electricity raging through his body as he comes, impossibly hard and impossibly long and all he knows is the voice above him leading him through it, dragging him up toward the light and asking of him the simplest thing that he'll ever do.
And he says yes.