Disclaimer: I don't own SPN.

I would've had this finished sooner but between Moments, work and my WIP fic (which currently has 34 completed chapters), I've been a bit busy! I've been meaning to do something like this for AGES and I'm so glad I finally got around to it! :D If this is popular then I might do a LOT more prompts like this ;)

Also, I'm no expert on BDSM. All I have are several amazing fanfics that I've read and my research (which took about half an hour before writing this), so don't hesitate to tell me if I've messed anything up!

Thanks to masterjediratgrl31 for your review :)

4. Safe, sane and consensual

Castiel frowned at the computer screen. When searching for more activities for him and Dean to do in bed, he'd never thought that this sort of thing could be considered sexually appealing. He didn't even know if Dean would enjoy it. Sure, Dean loved to 'bottom' and he loved to be controlled but Castiel wasn't sure if this would be appropriate. Dean was very masculine, after all, and between that and his natural instincts due to his upbringing and hunter life, Castiel didn't know if he would relinquish control in this way. But this took a lot of trust between both parties and Castiel immediately knew that he would trust Dean implicitly to do this to him, so maybe asking Dean was the best way to go – maybe Dean would agree if Castiel was the 'sub'.

His decision made, Castiel picked up Dean's laptop and headed for their room. To his relief, Dean was already there and his human grinned at him as he entered.

"What's up, Cas?" Dean said. Castiel took a nervous breath and sat down next to Dean.

"I…wish to try something new," he said. "And I understand if you do not wish to do it but I thought that it might…what's the phrase? 'Spice up our sex lives'."

Dean snickered.

"Give that here." He took the laptop from Castiel and began to scroll down. Castiel looked away when Dean's eyebrows furrowed, feeling embarrassed and trying not to show it.

"You've seriously been thinking about this?" Dean said. Castiel nodded, still not looking at Dean. "Hey. Look at me, angel."

Castiel reluctantly looked at Dean and saw that his human had a soft smile on his face, rather than looking repulsed or angry.

"I thought that it might be interesting," Castiel said quickly. "The essential principle of BDSM is 'safe, sane and consensual' – everything that we do would be as safe as possible, we would be of totally sound mind and nothing would be done without explicit consent. And we would both have a safe word to use in case we felt threatened or didn't like an activity –"

"Just lemme read, Cas," Dean interrupted. Castiel felt silent, allowing Dean to keep reading the information on the website. His face didn't give anything away and Castiel swallowed nervously when Dean finally looked up from the laptop.

"You seriously want this?" he said.

"Only if you do," Castiel said immediately. "I thought that it might be interesting and a change from the 'vanilla' sex that we have. Not that I'm bored with that because sex of any kind with you is always extremely pleasurable but –"

"Says here that we should write out a contract to outline what we're comfortable with and what we won't do," Dean said, squinting at the screen. Castiel froze. Was Dean really considering this? "Grab a pen and paper, Cas."

A wide smile split Castiel's face and he scrambled to find pen and a paper.

"Golden showers are out," Dean said straight away, scribbling something down on the right side of the paper. "We're not peeing on each other. That's gross. Anything to do with pee, poop, vomit…that's all out."

Castiel nodded. That was reasonable and the thought of urinating or defecating on Dean was just abominable.

"Flogging," he said. "And spanking. I would never feel comfortable hurting you like that. I know that some people derive pleasure from causing their partner pain but I could never hurt you, Dean."

"Yeah," Dean agreed heavily. "After Hell and all the crap we've been through…we've hurt each other too much, Cas. I'm not beating the crap outta you again, even if it's just role play. No flogging, spanking or torture."

"Minor pain is acceptable, though?" Castiel said. "Such as hair pulling and scratching and biting?"

"That stuff's cool. 'S just all the heavy crap that we're not doing."

"What about binding each other? What are your limits on that, Dean? I am perfectly happy to be bound in any way because I trust that you will not let me get hurt or take advantage of me in that way."

Dean swallowed and looked down.

"I – I trust you too, Cas." Heat blossomed in Castiel at Dean's admission of trust. "Just no being suspended, okay? I – that happened a lot in Hell. With chains and hooks and stuff. And that's another thing: can we not use chains?"

"Of course," Castiel said immediately. "No chains and no suspension. How much are you willing to be bound? I'm okay with being tied up completely and even blindfolded and gagged. But if one of us is gagged then we need a way of communicating without our safe word."

"I'm cool with that stuff," Dean said. "And when we're gagged…how 'bout we just shake our heads?"

"But you often shake your head when you are in the throes of passion," Castiel pointed out. Dean's cheeks flushed pink. "How about a certain action? Such as snapping fingers? That's something that neither of us ever do when having sex."

"Snapping fingers it is," Dean said. "Here, lemme research safe words."

He typed something and then clicked on a link.

"Says here that the most common kind is colours. Red for 'stop', yellow for 'slow down' and green for 'keep going'. Sounds simple enough."

"Those are common words," Castiel pointed out. "How about words that we are certain never to say during sex?"

Dean nodded.

"Okay. Gimme a minute." He closed his eyes, thinking. "How about…Lawrence for red and Kansas for yellow?"

Castiel nodded with a small smile, understanding Dean's reasoning behind choosing those safe words. And those were two words that he would never say while caught up in ecstasy, so Castiel would immediately know to stop or slow down.

"I think…Hell for red and Purgatory for yellow," he said after a moment. "I would never say Purgatory in any normal conversation and I never say Hell in bed. Lawrence and Kansas hold more significance for you than me."

Dean grinned and ruffled Castiel's hair. Castiel swatted his hand away, though he was smiling.

"Okay, so we've got safe words and no-go scenarios," Dean said. He paused and frowned at something on the screen. "Apparently, some subs don't use the safe word because they feel weak and wanna make their partner happy and then the top feels guilty for not reading their partner's body language and feels like they've damaged the bottom or something."

Castiel grimaced, knowing that both he and Dean would not use their safe word if it meant possibly disappointing their partner.

"Promise me, Cas," Dean said seriously. "Promise me that if it gets too rough, you'll use your safe words and won't hold out just to make me happy. Otherwise, I'm ripping up this thing and we'll forget this ever happened."

Castiel felt warm fuzziness spread through him at how much Dean cared for him.

"Only if you promise the same," he said. Dean nodded straight away.

"Done." He scratched out their safe words on the paper. "So, Cas, what d'you say about role play?"

Images of Dean in various costumes flashed through Castiel's mind and he felt a stirring in his pants.

"Definitely," he said vehemently. Dean grinned.

"Great. 'Cause I can't wait to see ya as a hot professor when you're topping."

He wrote something down.

"That's something we've gotta talk about as well. Topping and bottoming."

"From what I've read, a lot of couples choose one person to top and one person to bottom," Castiel said. "Tops aren't always dominant and bottoms aren't always submissive."

"Yeah," Dean grinned. "Have you seen us? I'd say we're both dominant but hey, we like shoving our dicks into each other and having the other's dick shoved into us."

Castiel felt himself flush at Dean's crude terms.

"But it also says that some couples alternate topping and bottoming," he said. "I think that if we are going to have normal sex, we can be caught up in the moment and see where it takes us. But if we are going to engage in bondage or role play then I feel that we must discuss it beforehand."

"Agreed," Dean said. "We're getting there, angel." He reached out and tugged Castiel close, giving him a one-armed hug. "I've got so many fantasies about doing all kinds of stuff to you…and you doing stuff to me." He looked away, his cheeks pink. "I just…never figured you'd be into that stuff."

"Apparently, I am," Castiel smiled. "Is that everything?"

"Scenarios," Dean said after scrolling down. "Doctor and patient…well, we sorta did that when you got that Doctor Sexy costume, didn't we?"

Castiel laughed and nuzzled into Dean's neck, remembering the times when he was jealous of a fictional character.

"Escort and client…oh, I like that. Master and slave…you okay with that one?"

"So long as it is not too demeaning," Castiel said. Dean nodded.

"Teacher and student…oh, all the times I've dreamed of being a naughty student with you as my hot professor…"

Castiel groaned and buried his face in Dean's neck in embarrassment, ignoring how his glasses pressed uncomfortably into his face.

"Pizza man and babysitter?" he muttered, his voice muffled. Dean let out an explosive laugh and kissed Castiel fondly before returning to his research.

"Okay, this stuff is really weird. Incest play? Animal play? Yeah, we're not going there. Rape and prisoner scenarios?"

Castiel shivered, memories of April and her taking charge swimming back to the forefront of his mind. Dean immediately set the laptop aside and pulled Castiel into his lap.

"I…wouldn't mind the second one," Castiel said quietly. "I must admit…the thought of you kidnapping and binding me is…appealing. Just…not the first one. Not after…April."

"Definitely not," Dean agreed, stroking Castiel's hair. Castiel purred and leaned into the touch, relaxing against Dean's chest and feeling Dean's cheek rest on top of his head. "You know what we've gotta do, Cas? Pure and innocent angel, corrupted by the sinful human."

Castiel chuckled softly.

"That's not a scenario," he said. "That's a reality."

"I know," Dean said proudly. "I corrupted an angel. That's enough to send anybody to Hell."

"Not if the angel chooses to be corrupted," Castiel retorted. "And not if the angel was never corrupted in the first place but simply shown a better path."

Dean was silent. When Castiel looked up, his human immediately pressed his lips to Castiel's and the ex-angel reciprocated, tangling his fingers through Dean's hair.

"Okay forget about the kinky stuff," Dean murmured, his voice a low, husky whisper. "Right now, all I want is to just stick my dick inside you and pound away."

Castiel shuddered, hot waves of arousal coursing through him.

"Then what are you waiting for?" he demanded. "Get your dick inside me this instant. Fuck me now, Dean."

Dean groaned loudly and shoved Castiel down on the mattress before carefully placing the laptop and contract on the ground. He then turned and pounced on Castiel, attacking him with kisses and nibbles. Castiel whined and tipped his head back so that Dean could bite his throat. Dean sucked several bruises into Castiel's skin before gently taking Castiel's glasses off and shifting to the side to lay them on the bedside table and fumble in the drawer.

"Where's the damn lube?" he growled. Castiel whimpered and whined, trying to get Dean to return to his previous task. There were some days where they took their sweet time, engaging in plenty of foreplay and trying to bring each other as much pleasure as possible, and then there were some days where it was a race to prepare the bottom and then pound away in rough, hot intercourse. Castiel knew that this case was the latter and he felt hot and sweaty in anticipation of having Dean thrusting hard into him. He needed Dean inside him right now!

Castiel growled in approval when Dean finally found the lubricant and then he grabbed Dean's hair and pulled him in for a rough, nearly painful kiss, where Dean bit his bottom lip and attacked his mouth. His human pulled away after a moment and Dean and Castiel stripped as quickly as possible, ripping shirts off and tugging down pants and underpants. Once they were both naked, Dean coated his fingers in lubricant and stuck two inside Castiel at once. Castiel groaned in pleasure as Dean began to scissor him open and it felt like only seconds before a third finger joined in. When Dean's fingers brushed over his prostate, Castiel cried out and gripped Dean's biceps so hard that his fingernails left red marks in his human's skin.

"That's enough!" he ordered. "I need you to put your penis inside me right now, Dean!"

Dean chuckled – and it was a low, dark laugh that made Castiel's swollen penis feel even harder and made his heart race faster – and brushed his fingers over Castiel's prostate again.

"You didn't ask very nicely, angel," Dean said smugly as Castiel moaned long and loudly.

"Fuck me, Dean!" Castiel demanded. "Fuck me this instant! I need you to fuck me now or so help me –!"

Dean grinned.

"Well, if you insist," he said. He removed his fingers, took a moment to lubricate his penis and then lined himself up. Castiel wrapped his legs around Dean's waist tightly and all but forced Dean inside. He groaned loudly as Dean filled and completed him and let his head fall back as familiar pleasure overwhelmed him.

"How about I take this slooooow?" Dean said with an evil grin, rocking his hips very gently. This created enough friction to drive Castiel mad but not enough to satisfy him.

"How about you move and pound into me?" Castiel hissed. "You're aroused. I'm very aroused. I need you to fuck me hard right now!"

Dean's pupils were so dilated that it was very difficult to make out the thin ring of green around them. Castiel knew that 'dirty talk' drove Dean wild and that telling Dean to 'fuck him' would result in very hard and coarse sex, which was exactly what he desired.

"As you wish," Dean forced out. He pulled back and slammed his hips forward, ramming into Castiel hard. Castiel howled in pure, primal rapture as Dean hit his prostate and waves of unimaginable pleasure filled every cell of his body, short-circuiting his mind. Dean began to thrust roughly and pound into Castiel so hard that the ex-angel knew that he would be very sore afterwards but Castiel was thrilled at the prospect; this was the sort of pain that he loved and enjoyed. With every forceful thrust, Dean's penis drove against Castiel's prostate and the growing ecstasy reduced Castiel to a whining, whimpering, babbling mess, only able to say Dean's name – and even that was broken.

"You close, angel?" Dean grunted. Castiel could only nod as he felt heat settling in his stomach and his groin tightening and he tried to reach up and wrap his arms around Dean's neck but he was too weak and his mind was too foggy to focus. Chuckling darkly, Dean clasped his fingers with Castiel's and began to pound even harder, burying himself deep inside Castiel. Castiel began to sob, tears streaming down his face at the raw euphoria sparking and jolting through him, and he groaned in horror when Dean's pace slowed.

"Okay?" Dean said, barely coherent. "Crying…happy? Or –"

"D-Don't stop," Castiel snarled, desperate for release and angry that Dean was denying him his orgasm. His legs tightened around Dean's waist and he thrust his hips up, fucking himself on Dean's penis and letting out a choked cry when he hit his prostate. "F-Fuck me. Fuck me hard, D-Dean! D-Don't stop!"

Dean immediately picked up the pace again and Castiel was once again reduced to whimpers and sobs. The familiar heat of his impending climax was now spreading through his abdomen and Castiel felt pure, hot energy shoot through him, his muscles seizing in anticipation. As soon as Dean's shaky hand wrapped around his penis, Castiel knew that he was lost. It only took three strokes to bring Castiel to his climax and he howled and screamed as his vision went white and he exploded like a supernova, stars bursting behind the eyelids that he'd squeezed shut. He heard Dean bellow as his orgasm also hit and then hot, sticky liquid was being pumped deep inside Castiel, who had collapsed in a limp heap on the bed, his legs falling away from around Dean's waist. He felt Dean sag bonelessly on top of him, breathing heavily.

"W-Wow," Dean gasped, pressing a clumsy kiss to Castiel's lips. "You're awesome, Cas."

Castiel nodded, unable to move at all. He felt Dean begin to pull out and he whined, not wanting to lose the sensation of being full and complete.

"Don't go, Dean," he complained. "I like having you inside me."

"You can't seriously wanna go for another round?" Dean said disbelievingly.

"I am physically incapable of 'going for another round'," Castiel panted. "But I – I enjoy having your penis inside me, even if we are not focusing on climaxing. It is as close as I can get to you without the ability to see your soul."

Dean's face softened and he shifted further up to press a kiss to Castiel's sweaty forehead. However, this made his penis brush against Castiel's prostate and in his post-orgasm condition, Castiel couldn't bear it.

"N-No!" he said, stars swimming before him. "Get it out! Get it out!"

Dean immediately pulled out and cupped Castiel's face.

"You okay, angel? I didn't hurt you?" he said worriedly. Castiel shook his head.

"I seem to be hypersensitive after experiencing my orgasm. I can't…"

"I get it." Dean rolled off Castiel and then pulled him close, so that Castiel was fitted against his side. Castiel threw his arm over Dean's stomach weakly and looped his leg over Dean's, in order to pull him as close as possible. The physical sensations of sex were nice but Castiel knew that it only felt this pleasurable because he loved Dean so much. If given the choice, he would choose to simply be close to Dean and hold him close for the rest of his life rather than have lots of sex for the sake of it and he knew that he only liked to have sex with Dean for the pure closeness of the act.

"Oh, God," Dean said, combing Castiel's damp hair with trembling fingers. Castiel purred and closed his eyes. "I can't wait till we start all this kinky stuff if that's what plain sex is like."

Images of Dean tied to the bed and at his mercy made Castiel shudder with desire. He just hummed in agreement and nestled into Dean's side, trying not to show any sign of the fantasies that were currently flashing through his head.