Dean was his favorite plaything.
Ever since he had first taken control over Dean back when he was seventeen, Sam had worked hard on tweaking and adding to the specific spell he had initially come up with. In the beginning, he had only wanted a sex toy, someone to practice on and have kinky fun with.
But before long, Sam realized that Dean could be so much more. Dean was, after all, first and foremost a lethal weapon. And Sam asked himself why he shouldn't make the most of that potential.
So he turned his big brother into the perfect combination of sex slave and ruthless warrior.
And since he got tired of constantly having to repeat the damn spell whenever he wanted Dean to do his bidding, Sam added a simple yet effective trigger.
Whenever Guns 'n Roses' "November Rain" played, all Sam had to do was give Dean an order, and Dean would obey.
The first few times, it was a heady experience. Later on, it became all but routine. When they were on the road, all he had to do was hit play on his phone. The song was, for obvious reasons, the number one on his playlist. Once the first few chords started playing, all Sam had to do was tell Dean to give him a blowjob, to crash Baby into a tree, or to kill someone, and Dean obeyed without hesitation.
Not that Sam would ever order Dean to crash Baby; he loved the Impala way too much for that.
But that was how Benny had found his early demise. Not to mention Kevin.
And really, sooner or later, he would make Dean kill Cas as well. The damn angel really got on Sam's nerves lately.
Now that Dean had gone to the dark side, he made an even more interesting plaything.
Sam loved it.
This Dean was ruthless, had no conscience and enjoyed violence. Whenever Sam allowed, Dean got really creative in his kills. And Sam allowed. Oh yeah, he did. He encouraged Dean, actually. It was a joy to watch his big brother dismember, disembowel, completely tear apart a monster until nothing but blood splatters and tiny pieces of flesh was left.
Of course, living in the bunker with a demon made every day...interesting. It was like dancing with a tiger--always waiting, always anticipating the big purring cat to turn on you, to growl and bite, to tear your throat out and slash you into shreds with sharp claws.
But then again, Sam mused, what was life without a little excitement?
Granted, he had to give Dean regular doses of human blood to keep him at least somewhat malleable. The demon inside of Dean resisted Sam's conditioning, and really, Sam couldn't have that. He wanted his brother wild and untamed, but still under his control. So he kept his blood donations to a minimum, but made sure that the demon was kept in check.
And it was getting time for another feeding, but first, he wanted to watch Dean "demon out", as Sam called it affectionately.
He turned on the bunker-wide loudspeaker system and listened to the tinny rendition of "November Rain" blaring through the batcave. He didn't really know where Dean was currently hiding, but that was easily fixed.
Sam grabbed a microphone and turned it on. "Oh Dean?" he sing-songed into the mike. "Why don't you meet me in the dungeon? I have a new toy for you."
Sam put the mike back down and smirked. He had managed to summon and capture Crowley a few minutes ago. It would be so much fun to watch Dean torture the King of Hell. Just for a little while, of course. Sam was sure that Crowley could still be useful in future and didn't actually want him dead, of course.
It wasn't anything personal, really. Sam could have summoned any old demon. But he was bored, and he was craving some really good entertainment. Pitching Crowley against Dean promised to be a fantastic show.
Sam sauntered around the corner to the dungeon, wondering which torture implements Dean would pick this time. But then he heard the sounds of fists pounding flesh, and the animalistic growl that his demon brother always emitted when he was losing complete control.
Sam smirked evilly. Not only would he get to watch some creative torture. Afterwards, he would get to punish Dean for starting early.
Two for the price of one.
What a perfect day.