A/N: In order for the beginning to make any sense whatsoever, you must understand my theory of Siren love. Siren saliva is like a slow moving drug that makes whoever has it in their system obsessed with the Siren, making them do whatever they think will make the Siren happy. Also, everything else becomes secondary to the Siren, including the Siren lover's own needs/wants/morals. If Dean has Nick's spit in his pipes, then he'll do whatever Nick says, regardless of whither he wants to do it or not. Got it? Good. In my twisted little mind, Siren poison is the Supernatural equivalent of heroin, and if that squicks you in the slightest, I won't be angry of you press the back button.

Disclaimer: Not mine, title taken from The Killers

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Nick told him to get rid of his necklace. The little golden amulet that had hung from Dean's neck as long as he could remember.

Dean threw it by the side of the road without a second glance.

___

Dean was covered in little droplets of blood. Dark red freckles to match the light brown ones he already had. Killing was never his favorite thing, but he would do it for love.

The love of his Nick.

It had to have been about the tenth kill he'd made for Nick, though he'd tried to lose count before. Dean leaned his forehead on the cool tile wall of the shower, and let the hot water slide over his back. He closed his eyes, so he could miss when the water turned that eerie pinkish shade.

It had been a girl this time. Some girl from a club that had been hitting on Dean.

Nick never had been one to share.

___

The Impala had a dent in it, again. This time from Nick getting them chased by a police car and, cackling like a cartoon villain, attempting to drive it into a ditch. Thankfully, the cop car had lost them at the last second, and Nick decided to keep Dean's baby on the road. They had staked out in an abandoned gas station in the middle of the fucking desert, where everything tasted like dirt and smelled like sand.

The good thing about old gas stations was that they had plenty of equipment. Dean had pretty much everything he needed to take care of his car. The dent was definitely not going to buff out. Dean sighed and started looking for anything that could be used to get his car back into shape. There was a slight breeze.

"What are you doing here, Dean?" deadpanned a voice from behind him.

"I'm not supposed to talk to you," Dean replied, still looking through his supplies. Nick had forbidden him to talk to any angels.

"Dean," Castiel said warningly. "I will stop you."

"Are you threatening him?" Dean asked coldly, his hand wrapping around a crowbar.

"I am." Fast as he could, Dean turned, aiming the crowbar at Castiel's head. No one threatened his Nick. The angel stopped the metal bar one handedly, just before it hit his temple.

Their eyes locked, the angel staring impassively back at Dean. And then, faster than humanly possible, because Castiel wasn't human, the angel's hand snaked out and tapped Dean's forehead lightly.

Everything went black.

___

Dreaming, Dean saw what happened. Or maybe not exactly what happened, but he definitely saw something.

Castiel went to Nick in the room they had been sharing at the back of the gas station. Nick was sleeping on an under inflated air mattress in the corner. In his head, somehow both standing next to them and hovering above them at the same time, Dean tried to warn Nick.

"Siren," Castiel growled. Nick stretched, groggily waking himself up. He had always slept in later than Dean, something he found both annoying and oddly endearing at the same time.

"Dean?" Nick asked muzzily. He propped himself up on his arms and flexed before opening his eyes.

"You will release him," Castiel ordered, his voice filled with a wrath that Dean hadn't really thought possible before that point. Holy wrath.

"And if I don't?" Nick snarked, waking fast in the presence of a threat, it came naturally to him, a damn good ability to have, in Dean's book. Though he also seemed to share Dean's inability to stop being a cocky bastard at inappropriate times. Angels waking you up with seemingly full intent to smite being a damn good time to show some respect.

Respect that Dean was going to have to teach him after this. If there was an after.

"I will destroy you," Castiel said, and it was the destroy part that scared the shit out of Dean. Like the word kill was too small to describe what the angel was going to do to his Nick.

Nick smiled. "I dare you." The corner of Castiel's mouth twitched upwards, almost too fast for Dean to see it. Castiel stepped forward, calmly, but with an edge of repressed anger, a storm about to break over the room. Nick grinned, not even getting off the bed. Cocky as ever.

Dean wanted to scream at him, make Nick run the fuck away and hole up somewhere that no one could find him.

"He won't thank you, y'know," Nick said, making Castiel pause. "Even if I die, he'll still love me."

Castiel took the last few steps between him and Nick.

"Dean is sleeping. Stalling will not make him come for you."

The grin slipped off Nick's face, leaving his expression blank and terrified. Slowly, ever so fucking slowly, Castiel put his palm on Nick's forehead, letting his long fingers rest in his hair.

"It won't stop," Nick said. He was panicking, Dean could tell just from his tone. "He'll never stop loving me."

Castiel didn't seem to care.

Dean's limited dream vision whited out when Nick, his Nick, started screaming.

___

He woke up later. Hours, minutes, days, he had no clue. Just, later.

For the first few seconds all Dean felt was a mild, sleepy confusion at waking up on the side of the road with dirt in his mouth, then he remembered Castiel. Castiel threatening Dean's Nick. His stomach plummeted to somewhere around his ankles.

"Nick!" Dean called, climbing to his feet and hightailing it to that room at the back of the gas station where they had been sleeping.

The door was open. Nick couldn't sleep with the door open.

His Nick was laying on the mostly deflated air mattress, eyes closed. He didn't look so hot.

"Nick," Dean said again, softer. He couldn't remember ever feeling as scared as he had right then, it made him feel like a kid again. A five year old, waiting to see if the love of his life would open his eyes. "Nick, wake up."

Nothing.

Dean knelt on the bed, his weight pushing Nick up a few inches as the air in the mattress compressed. His head moved, tipping to the right in a loose, boneless way that made Dean want to puke. He reached out his hand, the hand that wanted to shake and was only stopped by sheer stubborn force of will, and pressed his first to fingers to Nick's neck. No pulse.

Dean withdrew his hand and pushed it through his hair. No pulse, but that didn't have to mean anything. Sometimes pulses were hard to find, forget about a lifetime of patching up people after hunts. Dean didn't even believe that in his own head.

Nick's lips were pressed together, Nick always slept with his mouth open.

Nick wasn't sleeping.

___

After more or less three hours of Dean kneeling at Nick's side, then sitting on the air mattress, just a deflated tarp on the hard floor, to fitfully dozing, Castiel came back. Dean wasn't even aware of him at first, being in the middle of one of his headaches. One of the slow pounding migraines that he got when he was away from his Nick for too long, headaches that were always banished by Nick's long kisses that made his lips numb.

"Dean," Castiel said, announcing his presence with that single syllable.

"Fuck off," Dean growled. The angel should show up later, when Dean was in the right condition to kill him. Kill him for killing his Nick.

"Dean, you have work to do." Dean had no choice but to laugh at that, even though it felt like two chunks of his brain were grinding together.

"I don't work for you," Dean said, holding his hand on his forehead to stop it from exploding. "I'm not yours." He took his hand off his forehead and screwed his eyes shut, rolling up his right sleeve. On his shoulder was Castiel's mark, and over it was Nick's, a thick white scar made with a kitchen knife, while Dean had sat as still as he could and Nick whispered in his ear.

"You're mine, Dean."

"I'm not yours."

"You are the Lord's." Dean laughed again, his head splitting.

___

Nick was changing. Of course, Dean knew that Nick wasn't human, it just hadn't seemed to matter until Dean started to see it. First his Nick's lips turned from pink to a decayed looking brown. There were matching circles around his eyes, and his ribs were starting to show through his skin. Whatever his Nick really looked like, it looked long dead. Wasn't that just hysterical?

For the first time in what felt like weeks, Dean pulled himself to his feet, wincing as the sudden movement made his headache increase. He rubbed at where the pain seemed to be focused, right above the bridge of his nose, between his eyes.

He cracked open his eyes and scanned the room, spotting a wrapped sandwich and water bottle in the corner that had definitely not been there before. Castiel had made a peace offering.

Dean left the sandwich, but grabbed the water bottle because he was angry, not stupid. He went outside and sat down leaning against the outside wall of the gas station. Even though he had just slept for what felt like most of his life, he was damn tired. After a brief rest, just long enough for his headache to settle, he made his way over to the Impala. The trunk was unlocked, being in the middle of nowhere like they were.

Dean pulled out the first gun that touched his hand, a sawed off shotgun. He walked back over to the wall and sat, taking a long drink from the water bottle.

The gun wouldn't kill and an angel, but it would hurt. Probably.

___

By the time Dean's eyes were half lidded with sleep and an effort to keep the sandy wind out, Castiel showed up. With a low whoosh he appeared in front of Dean, stepping effortlessly out of thin air.

Dean reflexively shot him where his heart was supposed to be. It didn't seem to faze the angel much, so Dean's next shot took out his left kneecap. Castiel collapsed, landing on his good knee and his palms, leg unable to support him.

"Dean," Castiel growled, staring at him. "You don't want to do this."

"Really?" Dean asked, taking a swig from the half empty water bottle, one hand keeping the gun aimed at Castiel. "Because I think I do." Castiel brought one fist forward, holding it level with his shoulder.

"Do you remember Sam?" Castiel asked. "Your brother?" He opened his fist, and out came a little gold pendant hanging on a black string. "You killed him two weeks ago."

Yeah, Dean remembered it. He killed a tall guy with floppy hair just before his first one of Nick's mind numbing kisses. Then he'd pushed it to the back of his mind with the others.

"Yeah. Your point?"

"Think about it, Dean," Castiel said, staring hypnotically into Dean's eyes. "You raised him. You took care of him. You saved his life countless times."

"Your point?" Dean repeated. Castiel was trying to guilt Dean into sparing him. It wasn't going to work.

"You could get him back." Dean paused.

"What about Nick?"

"The Siren doesn't have a soul. Sam does."

"No deal." Castiel sighed, drawing the necklace back into his fist.

"Think about it, Dean," the angel said, vanishing. There was two bullets left lying on the ground.