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By the time Dean realised what Sam was up to, it was already too late.
“Demon blood, Sam? Demon blood?”
And yeah, maybe some part of him was withering under the weight of his brother’s judgement, but the blood was still hot on his tongue and all he could really think about was how good Dean would feel right now. How fucking tight he would be and how easy it would be to control him with the surge of energy in his veins. He barely even noticed the dead bodies on the ground, or the fact that there was still blood smeared all over his face. He wanted Dean. Now.
It was second nature to send a tendril of power curling down Dean’s spine, pinching off blood vessels and lighting nerve endings. He’d done it so many times before and in two seconds flat he had his brother on his knees, screaming around a curse as his crotch ignited in pain. Sam was doing that. It was so easy it was almost laughable. Didn’t take more than a tweak of his mind and suddenly Dean was his.
He almost stumbled as he got to his feet. He was drunk with lust and power and the knowledge that no one would ever be able to deny him again.
“Sam!” Dean screamed. What a beautiful sound. Music to his ears. He wanted his name to be the only thing Dean screamed ever again. He had just drunk some lowlife demon dry and he had never been so full. He was bloated on it. Everything Ruby had promised him was in reach. He could step on this whole building and still have energy leftover. He could rip Lilith in two.
“Dean,” he said. A warning and a promise. His voice didn’t sound like him anymore. He was too powerful for that now. He flicked Dean upright with just a jerk of his mind, and sent him careening into a nearby wall. He felt like a god.
“Sam, stop it! Stop it!”
So Dean had finally worked out what he was capable of. About time. Sam wrapped a tendril of power through Dean’s clothes, and with a swiping motion he jerked the whole lot free. Dean struggled in his grip, trying to fight the invisible force that held him against the wall.
Sam stalked up to him, lifting him clear off the ground as he went until Dean was hovering a few inches off the floor. The perfect height. He forced Dean’s knees into a bend, but kept his legs far enough apart so he could step between them easily.
“Dean,” he said again. Worshipful. He put his hands underneath his brother’s thighs, and spread backwards until the tips of his fingers tickled the crack of Dean’s ass.
“Get the fuck off me,” Dean snarled. Sam leaned into his personal space and breathed deep. He rubbed his still-wet face against Dean’s neck and then licked at the mess he had made, lapping the demon blood straight off his brother’s skin. Dean writhed and jerked in his hold, and Sam pressed more power into his cock and balls, making them swell and burn. Dean screamed, and usually by now he would be begging Sam for reprieve. He wasn’t begging this time, though. He was swearing and shaking and spitting with rage, writhing against Sam’s mind. Helpless in all but voice. He was hanging from Sam’s power.
Sam stepped in as close as he could, positioning himself right beneath Dean’s hole. He let Dean drop just slightly, until he was brushing the tip of Sam’s dick. And then he moved his hands up to frame Dean’s face, cupping his cheeks and staring into his eyes. “I love you,” he said serenely, meaning it.
“You’re not my brother,” Dean spat.
“No,” Sam agreed. “I’m better.” He dropped Dean straight down, spreading him with his power so he could keep his hands on Dean’s cheeks. Dean howled. Rage and arousal and helplessness spilling from his lips as if Sam’s cock was forcing it out, inch by inch.
They’d been doing this for months, but Sam barely had to retrain his brother’s muscles. Dean was just naturally tight. Welcoming and warm and, when Sam squeezed his balls, tense enough to make Sam see stars. He held Dean’s face in his hands and watched every emotion play out as he sunk deeper. When Dean shut his eyes Sam forced them back open, gluing his eyelids into position. He could kiss Dean now, if he wanted. Or kill him.
He didn’t do either of those things. He didn’t want to. Mostly he just wanted to possess him. To be inside him. To get so deep that Dean would never not know the feeling of Sam.
The tendrils of his power writhed as they, too, sought access. Around Dean’s neck. Into his hair. One of them wrapped around Sam’s cock. Another one lifted Dean by the waist, then dropped him back down, forcing him wide around the combined thickness of both Sam’s cock and the tendril. Others swarmed Dean’s balls, pinching and sucking and rolling them. Even more wrapped around his cock, already so full from Sam’s mental ministrations. One of the thinner ones was first to reach his slit, and Sam gave it access, letting it wriggle in to touch Dean from the inside, too. Dean swore vehemently, and another tendril cut him off, plunging into his mouth. Dean couldn’t see the power that Sam was wielding, but he could definitely feel it, stretching him out and filling him up and wrapping him tight, so tight, so he couldn’t do anything but take it.
Sam wanted to be deeper than his body would allow, but he could reach any part of his brother with his mind, and he did just that, skating along every inch of skin, inside and out, reaching in to rest along every rib, every muscle. He touched Dean’s heart, his real one, delicate and careful and with all the reverence it deserved. And he kept Dean’s eyes open so he could watch as Dean felt it. Every twist and pull and touch. The pulsing rhythm in his ass and the power everywhere else.
“You’re mine,” Sam murmured, not with his mouth but with his very being, etching it into Dean’s insides.
He didn’t bother rushing. He was done with caution. His eyes were black where they met Dean’s. He was stronger than Ruby had ever guessed. And so what if Dean knew what he was? He was powerful. Too powerful to care.
It took him years, or maybe only minutes. He let himself enjoy every inch of his brother. Every squeeze of him. When he finally emptied himself it was only a force of habit that had him reaching for Dean’s own response, pulling the tendril out of his mouth at the last moment so he could drink the sounds in as Dean came, loud and shaking. His eyes were dry but there were tear tracks down his cheeks that Sam licked clear.
“You—” Dean coughed, tried again. “The curse. It was you.”
Sam didn’t try to deny it. He was still inside Dean, and he twisted gently, relishing the overstimulated moans he pulled out.
“Sam,” Dean tried, hoarsed down to a whisper. “Fight it, man. Please.”
“I am fighting,” Sam told him. “Fighting Lilith. When she’s dead there won’t be anything to keep us apart.” With a flick of his fingers, the tendrils still inside Dean solidified, plugging up his ass and cock. Sam reconfigured their shape so Dean wouldn’t be able to remove them. Not without Sam’s power. “It’s easier this way,” he whispered. “You’ll never have to worry.”
“Sam, God, please don’t do this.”
He licked the last of the tears off Dean’s face, and solidified the tendril around Dean’s neck, too, turning it silver and metallic. He etched his name into it. In Enochian and English. Just because he could. No one would see Dean and believe he was free. No one would question Sam’s right.
“You’ll come to see it my way,” he murmured. “Soon enough.”
His eyes refused to turn back to normal, so he left them black.