Disclaimer: Supernatural belongs to Eric Kripke and WB. This was just written for entertainment
Sam/Dean entry for spnpairingbingo
Asphyxiation entry for Fandom Level

Sam stood in position and enjoyed the image in front of him.

When he planned his life as a teenager this had never been a part of it, being in a BDSM club and waiting for his Dom to start playing but now he couldn't imagine not having this, these moments when he was allowed to be free. Free of making decisions, free of saving people, free of the past and the future, free of everything but the feel of being cared for.

Even when he had gotten to the point that he admitted to himself what he needed it had taken time to get there. Their lifestyle was not exactly helpful in finding a partner, let alone someone who fit his specific preferences and could be trusted.

He didn't even know when the idea of somebody else controlling his breathing got him hot and bothered but he still remembered the moment when some random monster they were hunting choked him... and he got off on the feeling, absolutely surprising himself.

Being a Winchester he reacted with denial and hating himself for the curiosity. Every cell in him told him how dangerous this was, how the wish for being controlled was wrong. And he ignored the fact that that specific voice sounded suspiciously like his father, the familiar sound of disappointment at whatever Sam was thinking of doing.

And he continued to think about it. From time to time at least. When he was alone and had some time or could daydream about it when Dean thought he did research. Then he did something about it, let out his urges and felt better for doing what he needed for himself.

Everything was well till that one day.

Dean came back to their motel room, the interviews over for the day and take out in his hands. Sam deserved a treat of some green leafy things and one of those ridiculous Starbucks concoctions for staring at the laptop in a non fun activity all day. "Hey Sam, time for a break. Eat it before it wilts."

He saw his brother lying on the floor, a bag over his head. He was there and checking for his condition before the take out had any time to spill on the floor.

Two eternal seconds of frantic activity told him that his brother was alive, breathing and only unconscious, Dean couldn't find any wound.

He adjusted Sam's position so he wouldn't choke if he vomited and laid one hand on the rib, felt for the tactile proof that Sam was breathing.

That was the day Dean learned of his particular kink, not that he ever wanted anybody to know about that.

And boy, was Dean angry at him. Not for his preference, even with admitting that it had surprised him, but didn't Sam know how dangerous that was when you were alone? That you should have somebody there with you you trusted in case something went wrong?

And then Dean forbid him anything like this as long as Dean himself wasn't there to keep Sam safe. Sam had problems hiding his hard-on at that declaration, seeing Dean there, all bossy and knowing he would actually go through with his disciplinary promises in a heartbeat if he had to.

The next time they were in a bigger city with more specialized stores Dean dragged him to get "equipment". While Sam selected the best mask for himself blushing the whole time, Dean lingered over the restraints and tools for disciplining. The idea gave Sam delicious ideas. Sam was a big and strong guy but the idea to be completely dependent on somebody else, somebody he trusted with absolutely everything and who was actually physically able to force him... Obviously his brother had been aware of that and was willing to take on that role on a broader basis than before.

It fit Dean. His big brother was a carer and nurturer, as much as people didn't understand it, this was just a variation of caring for his little brother. And he had always been bossy as all hell.

Sam stood in position, the mask on and waiting. When they had the opportunity they went to a club like here, with others who shared at least this part of their life. Dean looked glorious, all hot and dominant in his leather pants and vest, the designated club outfit that signaled "playtime" for them. Sam was in his playtime outfit as well, his newest mask on and waiting for his big brother to begin. He teased him, the rumbling of Dean's deep voice against his skin, the things he said.

When Dean finally blocked the tubes of his mask with his thumbs and Sam felt the loss of oxygen, Sam was happy.