The first time Cas has coffee as a human, the caffeine affects him like it does a small child.

Sure, Jimmy Novak's body was used to the rush coffee gave, but with Cas as the sole being inside the body, so it was as though he wasn't used to it.

It was like how Cas has never had sex. Obviously Jimmy had - his daughter was testament to that - but the (fallen) angel had never experienced the act. He hadn't the knowledge of what passion and physical intimacy between two people felt like.

Dean made it his mission to teach Cas all the things humans did that he hadn't had to experience - or endure - when he still had his grace.

Like showering, food, sleep and getting drunk. Dean very much enjoyed the latter.

Castiel was affected by the alcohol after only one beer. He words were slurred, and was leaning heavily against Dean from his place next to him on the sofa.

They were in a motel room, with Sam next door - they couldn't get a room with three beds, so they had to get two. Sam had won the ability to have his own room - Dean was sure he had used a trick coin - and so Dean and Cas were spending time getting drunk before they went to sleep.

Castiel was very touch-y when drunk.

His hand, the one closest to the blond, had found its way to Dean's thigh, and was trailing upwards, towards more sensitive areas.

The hunter had downed four beers by the time Cas had finished his first one, and so was pleasantly numb, and not too worried about what the blue-eyed man was doing.

His eyes went slightly wide when the fallen angel clambered to straddle his lap, but he didn't push him off. He just placed his hands on the dark-haired man's hips, holding him firmly in place.

"You're trying to show me human things, yes?" Cas asked, breath wisping across Dean's face, making him flush slightly.

"Yes…?" He croaked out, eyes flickering to pink lips.

"Well," Cas lowered himself slightly, and there was the perfect amount of friction, and damn, Dean was becoming aroused, "I thought you would be willing to show me some of the things you've been avoiding." He actually ground his hips down this time, and the blond actually moaned, "Like kissing. Sex. Physical intimacy."

Dean wasn't sure who kissed who first, but he was fairly certain it was himself. Their first kiss was frantic and frenzied, and the moan Cas let out when they pulled apart for air was damn near erotic.

"I suppose you're ready." Dean teased, dropping a quick peck to the slightly swollen pink lips. "I've still got a lot to teach you, though." He let out a fake sigh. "It might take the rest of our lives."

Cas smiled a rare, gummy smile, eyes pinching slightly in the corners.

"Well, we better get started then." This time Cas dropped a kiss to the hunter's lips. "I want to become a professional in these things."

"Well that could take even longer."

"Good."

The next morning, they sat in a booth in a nearby diner, waiting for breakfast. Sam was sending them a glare that had Dean slightly worried, he'd never seen that much fire behind one of his glares before.

"You two kept me up half the fucking night." The glare lessened slightly, the fire slowly going out. "I don't know what the fuck you two were up to, but I swear, if you're planning on doing it again, I'm going to make sure we stay in different motels. Did you even realise how loud you guys were?!"

Dean couldn't help it when he burst out laughing. Tears built in the corner of his eyes, and he held his arms across his stomach, his sides hurting from laughing so much.

Cas looked baffled at the blond, and that was when Sam noticed the discolouration on his neck. His eyes flickered to his brother's neck, and similar marks were present there too.

It took only a few seconds before he came to the realisation.

"Oh gross!" The younger Winchester covered his eyes, shaking his head, and scrunching his face up with disgust. "You guys made me listen to that!"

His face went slightly green.

"I need brain bleach."

That was when he noticed the tormented look on his brother's face.

"I'm happy for you, Dean." He explained, giving the couple a smile. "I just didn't need to hear you guys have sex. Little brothers should never have to endure that."

"Sorry bro." Dean laughed, relieved at his brother's acceptance. His hand found Cas' under the table, and he smiled.

He could get used to this.