Before:

"Ok then." Dean let out loud sigh, giving Sam and Castiel small, silver knifes "Cas, are you sure that will work?"

"Yes." The angel took the knife with certainty. "The protection spell made with the blood of angel, demon and human will neutralize the effect of witch's curse."

"And it'll buy us time to deal with her." Sam finished "Dean, we talked about this."

"Yeah, I know." His older brother agreed with zero enthusiasm. "But it's your blood we're talking about, Sammy. It's like using your freaking demon powers again!"

Sam gritted his teeth. He didn't like this any more than Dean. But they were in hurry and they couldn't find any friendly neighborhood demon in this forsaken town to bleed out.

"Believe me, Dean, I know." He growled. "Now, can we get it over with?"

Muttering something about "stubborn bitch" under his breath, Dean finally nodded.

Sam and Castiel approached the iron bowl waiting for them on the table. Chanting the Latin incantation, they cut their forearms. The blood started to drop eagerly, falling with small thumping sound resembling beating of the heart at the bottom of the vessel. In the moment two trickles met, the room was filled with the smell of ozone. Two-coloured smoke, red and blue, rose from the bowl, creating complicated spirals and symbols in the air.

The incantation came to the end, the smoke was disappearing slowly. All that was left in the bowl was liquid, golden substance.

"It is done." Cas declared, pressing the hand over his bleeding arm.

Now:

Later he will think that it all has started with small thing.

Sam raised his head from the laptop, feeling sudden rush of blood in his body.

"Cas is coming." He said.

Dean looked at him, brow furrowing in confusion.

"What? Now? Did he call you?"

"No…" Sam mumbled "I just know it."

Before Dean could respond to this weird answer, the room was filled with the sound of flapping wings and Castiel appeared beside the window.

"Hello, Dean. Sam." He carefully avoided looking at the younger hunter.

"Speaking of the devil." Dean's eyes darted between his brother and the angel.

Sam's eyes were glued at Cas, he was aware of his presence in almost painful way. He felt every inch of space between them and every beat of their hearts, pulsing in synchronized rhythm "come…come…come…" It was like a call from the deepest part of his soul, pulling him towards other man, forcing him to be as close as possible. Come… Come… Come…

With every strength of his will, he managed to look away and clenched his fists , knuckles turning white.

Dean coughed meaningly.

"Ok, Cas. What brings you here? Is it a new case? Or Crowley thing?"

"No, it is not." Castiel shook his head and faced the window, staring at the motel's parking like it was the most interesting thing he has seen in his life. "I wanted to make sure that you two are alright."

"Of course we're alright. Why shouldn't we be?" Dean get up from the chair and came closer to his friend. "And apparently Sam has new angel radar or something."

"What does it mean?" Cas turned quickly towards him, blue eyes narrowing in alarm.

"You tell me. But he knew that you're going to come before it happened." Older hunter shrugged "Ask him."

"Is it true, Sam?" Cas looked at him, for the first time, and Sam risked one brief glance at him. It send an electric spark through his whole body, a signal setting every blood cell he had on sweet, longing fire. It was even louder than the voice of siren he experienced once.

comecomecomecomecomecomecome comecomecomecomecomecomeCOME

Sam could tell that Castiel's heart sped up too and that his gaze became more heated than second ago. He was sure, he wasn't the only one hearing this call of blood.

"Yes." And you know it. "What's going on?"

Cas visibly paled and leaned on the wall, like all the strength abandoned him at once.

"It's impossible." He shook his head frantically. "You couldn't… you're not…"

"Hey, hey, hey, Cas? What is it? Talk to us!" Dean grabbed his arm and squeezed it hard.

Cas made an effort to compose himself.

"It's the blood spell we have performed week ago." He gently freed himself from Dean's grip. "Blood is powerful substance. It's pure life force, the root of one's being. And with supernatural creatures, like angels or demons, its magical powers are even stronger."

He took a deep breath before finishing, with hunters waiting in anticipation .

"The spell we used have two purposes. One, protection against evil. And second… it can be used as a bonding ritual." The last sentence was a shaky whisper. "Sam, I'm so sorry."

The silence in the room spoke volumes.

"Bonding." Dean finally said.

"Yes, bonding."

"Like, tying Sam to yourself, him being at your every command, bonding?" Dean's calm voice hide thousands promises of painful death.

"No!" The angel seemed to be honestly shocked "No, it is not a spell to make someone a slave! It creates mutual bond."

"So what, now you're married?" Dean huffed, looking at Castiel like he lost his mind. "And you lied to us to win Sam's love? You couldn't just ask him out?"

"I was not aware that it'll work." Cas was almost pleading "Sam, you have to believe me. There is one condition that must be fulfilled before ritual, if not, the spell won't work. The participants must have romantic interest in each other."

If Dean didn't know better, he could swore that the angel blushed.

"I knew that I had impropriate thoughts about Sam for a long time. But I was certain that my affection is unrequited."

Dean turned to his brother with a dangerous smile.

"Sam? Is there something you want to share with class?"

Sam's patience was running out. He found it hard focusing on Cas' words, the drumming sound inside his head was louder than anything else.

COMECOMECOMECOMECOMECOMECOME COMECOMECOMECOMECOMECOME

"Dean, I need you to get out." His voice was almost an animalistic growl. "Now. Before you see things that even hectoliter of scotch won't wash out from your memory."

Dean gaping in silence like a fish taken out of water would be hilarious, if anyone paid attention to it.

"You can't be serious!"

"Dean. Out. Now." Sam raised his head, meeting Castiel's gaze. The electric spark was even stronger this time, causing the short hairs on his forearm to stand up. Dean hesitated for a moment, before grabbing his jacket and storming out the room, stopping at the door to declare:

"This conversation is not over!"

Finally alone, Cas and Sam has stared at each other like they were the only people left in the world.

"The ritual isn't finished, am I right?" asked Sam

"No, it isn't. To complete it, we have to bond physically as well." Cas titled his head, trying to read Sam's expression. "Are you afraid?"

"Yes." Sam answered immediately. "And you are too. What are the consequences? Will we die if we're not together?"

"No. But we will always want to be together. We will be able to feel the other's presence and emotions. We will be always attracted only to each other. Sam." Cas took one step towards him. "If we do it, there'll be no coming back."

But this one step was what broke Sam's remains of strong will. He was moving towards angel, towards his future soul mate, and he wouldn't be even aware of that, if not for the drumming in his head and body getting louder and louder with every move, until it was filling his head and destroying every rational thought.

"I don't care." He whispered, claiming Castiel's mouth, moaning at the first brush.

Cas hands were at his back, clenching at the shirt and pulling him closer as he deepened the kiss. Their tongues were swirling as they bit and sucked at each others lips. But it still wasn't enough so they started ripping their clothes off, never stopping the kiss.

MOREMOREMOREMOREMORE the beat commanded.

It wasn't about a pleasure, it was only about possessing, giving, taking, being as close as possible.

Cas' skin was hotter than Hell, Cas' mouth were sweeter than Heaven, and their bodies pulsed as one in the rhythm of drumming song. They swallowed this sound and it swallowed them whole, until all that was left in their heart was them.

The call of their blood has changed, not as demanding and devouring as previous one, but steady and assuring.

togethertoghetedtogethertoge thertogethertogethertogether

"Together." Sam said as he bit hard on Cas' chest, just where his heart was beating.

"Together." Cas gasped, hand tangled in Sam's head "Forever."

The new sound has just begun.