Disclaimer: If you recognize it then I don't own it.

Pairing: Cas/Dean

Warnings: Omega!Dean, Alpha!Cas, references to Heat, a/b/o dynamics, mentions of knotting

He's terrified the unknown angel will figure it out. Doesn't want such a huge secret exposed when there are so many unknown factors involved. His brother's health. The angels wandering the Earth. Cas missing. And everything is so very much out of his control. It keeps spiraling out of control and he can't find his footing.

Dammit he just let an angel take over his brother's body and what if that was wrong? What if he made a horrible mistake and this whole thing is a lie? Or maybe Ezekiel is being honest…maybe he is on their side?

Dean stares at his brother. Sees the color coming back to Sam's cheeks. The life returning to his eyes and swallows down the words threatening to crawl up his throat.

The words that would reveal Dean's biggest secret in the world. His secret shame. The very fact that he's an Omega. Considered weak and not just any Omega. He's a male Omega. Nothing better than a bitch to breed and a hole to fuck. He's meant to be fucked, knotted and bred full. Stuck at home raising kids and waiting for his mate to come back. To use him.

There is only one who knows. That knows what he is and it's because the angel built him from the ground up. Had cradled Dean's soul in his grace and recreated the hunter's body. Atom by atom. Cell by cell. Knew every single part of Dean including what he was and had never treated him differently. Had kept the secret when Dean had asked him. Begged him to not say a word.

To take it to the grave.

And Cas had. Multiple times without a word to anyone. The Alpha angel had fought for him, died for him and protected him. His scent so familiar and comforting that upon each of his death's Dean hadn't been able to stop himself from mourning. From trying to drink the pain away.

Dean had started taking his suppressants the instant he'd managed to get somewhere for them after Cas had raised him from Hell. Had bought his special unscented soaps that Sam never touched because his brother preferred some organic shit that Dean wouldn't touch with a ten foot pole. It hadn't taken long before he was back to his typical 'scent' and no one had been the wiser. It had helped that he'd crawled out of the grave smelling like Hell-fire and death. Covering up the Omega scent he should have smelled like upon his resurrection.

"Dean is something wrong?" Sam's voice caught his attention and Dean turned green eyes to meet his brother.

He opened his mouth to answer and closed it. It was too late. Dean couldn't tell Sam everything. Couldn't let such a huge secret out that could be used against him when there was an unknown angel in the mix.

Dean was partly relieved he didn't tell Sam everything that had happened in Purgatory and the other part wondered when the secrets will stop. When they can stop lying to each other. He swallows and looks away because now he's thinking about it. The secret he took with him from Purgatory. The real reason he had almost gone insane trying to push the memory of Cas staying behind to the back of his memory.

"Cas…please. Dammit Cas. I'm burnin up." he's lying in a cave, shaking and burning and rutting into the ground. Everything rubs against him wrong and he needs. Needs something and with terror he knows exactly what it is…exactly who he needs right now. "Please Cas. I need you."

There is a flutter of wings and tears are sliding down his cheeks. A sob escaping parted lips and his fingers dig into the ground. Body seeking friction and relief. He's empty and his body knows it. Wants to be full. To be split open on a knot.

"Dean." it's breathed out and a warm hand is touching him. He can feel the blood and dirt and grime of Purgatory washed away. But it doesn't quell the fire. Doesn't stop the burn and need curling in his gut. He's only experienced a heat once when he'd taken one of Bobby's cars into town leaving Sam behind with the old hunter. It had been a horrible week and the moment it had ended he'd sought medication. Hidden the truth from everyone.

"Cas. Please please please. Make it stop." it's coming out in sobs now and Cas drags him close. Hands soothing down his back and carding through Dean's hair. "I can't…Cas I can't." his face is buried in Cas's trenchcoat and his fingers dig into the fabric. "Tired of dancing around it. Around us."

"Shhh." it comes out in Cas's rough voice and Dean bites the inside of his cheek. Wants to beg and sob and plead. "Angels mate for life Dean. There is no leaving or seeking another Alpha." his hands continue moving, "I can stay here with you. Keep you safe but I won't tie you to me for your entire existence. I can't do that to you."

"Fuck Cas. I want to be tied to you. Want you. Want your knot." Cas stares at him. Looks into his soul and crashes their mouths together.

"Dean. We'll find Cas. He'll be ok." Sam's hand lands on Dean's shoulder and he finds himself nodding. Watching how Sam's eyes fill with compassion and understanding. "I know how much he means to you. But we'll find him."

"Yeah." he shifts in his seat and Sam takes his response in a different way. Sighing and shaking his head. Both exasperated and fond at the same time.

"He's your best friend. Stop closing yourself off." Sam stands up and offers a slight smile. There is something else behind his brother's eyes and Dean barely holds back a shudder.

But fear is climbing up his throat when blue flashes brightly in Sam's eyes and it isn't his little brother looking at him anymore. It is an unknown angel in his Alpha brother's body.

"I'm sure we'll find Castiel." everything about Sammy is wrong.

Wrong wrong wrong.

His scent, his stance, his tone, his face…all of it is wrong and the Omega side of Dean whines low. Hates that its family is sick…that Sam feels off. Ezekiel cocks his head to the side and Dean wants to scream because the angel in front of him isn't Cas. The head tilt is Cas's. That curious expression belongs to his angel. His mate.

"I know." his voice comes out small but he clears his throat and gets to his feet. Won't let this unknown stand over him in such a position. Hates how vulnerable it makes him feel.

"Your brother is starting to heal." Ezekiel offers still staring at him and Dean hopes their agreement is binding. That the angel won't look into his mind. Will give Sam some privacy as well. "You should not worry so much. It cannot be healthy for a human."

Dean nods and takes a step away looking around the bunker. He wants to get out. Get some fresh air because right now he feels like he's choking. He wants to call Cas back. Listen to his mate's voice. Wants to find him and bury his face into Cas's neck. Surround himself in the scents of mate and safe and home because right now the bunker feels cold. It's missing warmth.

It's missing Cas.

Ezekiel steps into his space and everything in Dean freezes up as the angel stares at him. Breathing in and cocking his head to the side. "You smell…off." he trails off in an uncertain tone, "Not like most humans I have encountered."

A laugh catches in Dean's throat, "Probably my soap." it is weak and he shifts again wanting to get away. He's going to keep it a secret for as long as he can. It wouldn't be right for anyone else to find out before he could tell Sam. Because he needs to apologize and tell his brother of his shame. Of his fear. But also of his mate. To let Sammy know that he finally found something for himself and that Cas loves him. Cas cares for him and he's got a mate that will never leave him.

Prompt: A scenario where Omega!Dean tries to hide the fact that he's an omega (and Cas is his mate) from Ezekiel?