Castiel is an angel, so doesn't really have much concept of things, such as shame. Dean however, is a human, and should know better. Unfortunately for Sam, Dean Winchester doesn't really care what he does in front who.

Sam was overjoyed for his brother when he came to tems with his feelings for his feathered friend. For several years Dean and Castiel tip-toed around the fact they were madly in love with each other, leaving Sam to sit awkwardly in the corner. Their staring turned into blatant eye-sex after five minutes, Dean invaded Cas' personal space than Cas did to him, Dean would always find a reason to call Cas, or persuade him to stay when there was no real reason. The first Sam got confirmation of their love was when Cas came to him for advice.

Dean was outside the motel, washing the love of his life, whilst Sam sat inside, browsing the internet for a possible case. Whilst reading a police report, he heard the familiar flap of wings; spinning round he saw Cas stood by his bed, looking troubled.

"Cas?"

"Sam, I need your advice."

Nodding, Sam turned around properly in his seat and motioned for Cas to sit; "all right, what's wrong?"

Cas cautiously sat on the edge of the be and rest his hands on his lap; "human behaviour, confuses me. I think you're aware. When one human likes another, how do they show it?"

"...Likes? As, a friend? Or something more?"

Cas took a deep breath; "love."

Sam smirked; "ah... Well, usually, one will ask the other out."

"Ask them out?"

"Ask them on a date, then when they're on the date, 'love' will ensue."

Cas frowned; "I don't understand."

Sighing, Sam shuffled closer to Cas; "right. Who are you asking out?"

"...That's not of import."

"Dean. Ok. Ask him, if he wants to, go get a drink or something, or just ask if he wants to go out and let him choose what you do. Then, when the moment's right, slip in to the conversation you're madly in love with him."

Cas paused before shaking his head; "what if that scares him off?"

Sam smirked; "so it is Dean?"

"I would have thought that was pretty obvious, now Sam if you could focus."

"Yeah, sorry... It won't scare him off, Cas. He's in love with you too. Just go ask him out."

Cas nodded and stood up; "thank you, Sam."

The youngest Winchester watched the angel flatten his coat and walk out of the motel room. He ran to the window and pressed his face against it, watching Cas march over to Dean and engage in conversation.

That evening, Sam had had an early night, but was woken up to the door being kicked down. He reached under his pillow and held onto the gun lying there, when the people responsible came in to view. It was his brother, and Castiel, hands all over each other, kissing in the most disgusting way Sam had ever seen. Groaning, he rolled onto his side facing away from Dean's bed and pulled his pillow over his face; trying to block out the noises of the two men falling on to Dean's bed, moaning and laughing.

Since then, Sam had played his part of the third wheel perfectly. He spent the majority of his time looking at his hands or feet, as Dean had no qualms with kissing his lover passionately in front of his brother. He also had no problem with making love to the angel with his brother lying a few feet away, wide-eyed and disturbed beyond belief. Sam had walked in on the two being intimate more times than he could count; for some reason, Dean had no shame.

"I can't do it any more, Bobby. This is beyond ridiculous!"

Bobby sighed and took a swig of his beer; "look Sam, they're just, in the honeymoon stage, it'll calm down after a while.

"It's been going on for two months! Look, they're in there right now, probably having sex on your sofa!"

"I'll burn it, I never liked it anyway."

Sam sighed and rubbed his forehead; "you've got to help me. We're living in close quarters, I'm in the room when they're, doing stuff. Dean makes me drive so he and Cas can get dirty in the back seat, and... One time, I was sat between them, instead of getting up, Dean just leant across me and stuck his tongue down Cas' throat! I was trapped between the two swapping spit! For like, ten minutes!"

Boby frowned; "have you tried talking to him?"

"He ignores me."

"We've got to get them alone then."

Sam shrugged; "how?"

Bobby finished his drink and stood up; "come on."

The two hunters marched into Bobby Singer's house and found Dean and Castiel on the sofa, entangled in each others' limbs, mouths almost glued together. Sam leant down and grabbed Cas' shoulders, pulling him off his brother.

"Whoa, what are you doing?" Dean demanded, reaching out to grab Cas' hand.

"This has got to stop, boy," Bobby said, restraining Dean.

"What? You told us to just get together already, and now-"

"-Dean, the two of you are at it all the time! When people are in the room, it makes us uncomfortable! Just, calm down!" Sam said, glaring. Dean shrugged.

"So? We're just, enjoying each other."

"All the time? Dean, I'm your brother! I don't want to be in the room whilst you two are, y'know. It's giving me nightmares!"

"Fine. I'll get two rooms when we're on the road! Happy?"

Sam let go of Cas, who jumped down to Dean's side; "no, stop making me drive so you can get frisky in the back, stop making out in front of me, just, keep it to yourselves!"

Dean glared; "so, we can't do anything?"

"In front of me, no!"

"Whatever."

Dean managed to pull out of Bobby's grip and grabbed Cas' hand, dragging him out of the room to their bedroom, slamming the door shut. Sam sighed loudly and slumped down on the sofa.

"I give it a week until they're having sex across my lap."