A/N: Written as a sort of reaction to what I've been reading about 4.21. I think the following scenario would be so deliciously satisfying to see. Title is the translation of "apocalypse", from the Greek.
"NO! NO SAMMY DON'T DO IT LILITH'S THE LAST S…"
But Dean was too late. Sam had long become completely consumed by his desire for revenge, and by now thought he was too powerful to listen to his merely human brother.
Lilith burned up with a smile on her face, her last thoughts joyfully reveling in the destruction that would soon rain upon the world. It was too bad she'd never see it, but it was worth it, all of it. The beautiful Lucifer would soon walk free. She was happy to be a stepping stone to his resurrection.
Sam didn't see that, of course, too busy focusing on the bright sparks that ran over her body, feeling the satisfying rush of power as the demon was crushed into oblivion.
Finally, everything went silent. Lilith's corpse, the body she was riding still nearly pristine, fell to the ground.
Sam was about to yell his success to the heavens when the warm muggy night abruptly chilled. He heard a brief choked-off gasp from Ruby. The wan starlight was overwhelmed by a bright light shining all round him. Sam turned, searching for the source of the light, and what could've led Ruby to make such a pathetic little noise.
"You really should've listened to me, Sammy," Dean said as he stopped walking about ten feet in front of Sam. He was glowing from within, the almost painfully bright light forming a halo around him.
"You never once wondered why Ruby was helping you? How nice and helpful she was after going to Hell? Again? And you're supposed to be the smart one. But I have to say, she was quite useful. Corrupted you quite thoroughly. And helped bring about the apocalypse of course." Dean made a hand motion, palm downward, as if to settle a dog.
Sam found himself kneeling, none of his limbs answering the command to keep standing.
"The kicker is, you could've developed the very same powers just fine on your own. But looks like you'll always need someone to hold your hand. Who's the weakling now? But she still messed with you Sammy, and I can never forgive her for that." Dean made a sweeping motion in Ruby's direction, and black smoke was ripped from her body, sparking and whipping against intangible currents of power until the last glint of dying demon went out.
"So Sammy, how's it feel being the one to release Lucifer from his prison? Lemme tell you, I'm feeling fucking fantastic after being cooped up as a mortal for all these lifetimes."
Dean chuckled. "Now you're thinking I'm possessed by the Big Bad Morning Star himself. I'm seriously wondering how you even got into college, you're not thinking very creatively. What they hid away was the power, and locked the soul into a mortal body to be reborn forever, never to touch Heaven or Hell again. Most of the angels forgot all about that. So did the demons. I'm the same as I was yesterday...but better."
Dean rolled his shoulders, stretching his arms above his head as enormous wings made of light extended from his back.
"But now I'm back. Both sides were using us. But it doesn't matter anymore what they want. All that matters now is what I want. And right now I want you most of all."
Invisible hands yanked Sam to his feet and pushed him onto Dean. Strong hands came around to hold him an unbreakable embrace.
"Thanks to Ruby, you're so far gone down the demon path that I can control you completely. Do whatever I wish with you. And you'll like it," Dean spoke softly into Sam's ear.
"Let's go, Sammy. The whole world is ours."