A/N: This came about because I keep thinking what an idiot Davros was for wanting to destroy everything in creation because what would he and the Daleks do with themselves afterwards. This is my take on what would happen if he had succeeded. This is AU not only because of that but also because Davros has captured everyone, both the companions and their family and friends.
At last…his moment of triumph had come. His most hated enemy was powerless. Imprisoned in a holding cell with his precious human allies clustered around him, their hands on their heads as all of them silently watched the view screen. To his right, the freakish clone stood silently, a look of disbelief on his face. Davros chuckled imagining the fool was probably stunned at being caught so quickly after his botched rescue attempt. As the countdown neared zero, he couldn't resist a moment of gloating to his captives.
"Stand witness Time Lord, stand witness humans. Your strategies have failed, your weapons are useless and oh…the end of the universe has come."
"Davros, please, please I'm begging you to reconsider! Don't do this!" the Doctor pleaded.
Davros swiveled his chair around and faced him with a smirk on his face.
"At last, Doctor, I have you right where I want you. All of creation is about to be wiped out and there is nothing you can do. All that will be left are you and your beloved humans, besides us, of course. I have won, Doctor. After all this time I have finally triumphed over you!"
"3…2…1…DETONATE REALITY BOMB!" the Supreme Dalek said.
The Doctor's hearts caught in his throat as the twenty seven planets glowed with an eerie radiance. Then…it happened. Everyone watched in stunned silence as the beam was fired and all matter around the Medusa Cascade dissolved into glowing golden atoms and disappeared. The captives watched helplessly as the view screen followed the beam out into the cosmos and everything around it disappeared. While it happened, Davros couldn't resist gloating again and he let out a loud, insane cackle while the Doctor slumped to the floor of his prison, his hearts breaking as he thought of the trillions of innocent lives that were being snuffed out before their very eyes. Out of the corner of his eye he saw his clone doing the same thing and turning his head away so he wouldn't witness it. The Doctor glanced over at his friends and their family members, some of them were weeping quietly, some were just staring at the view screen in complete shock and Jack was gritting his teeth as he gazed at the screen in silent rage. The Doctor's eyes caught Rose's and he saw the silent despair in her tear filled eyes and he wished at this moment he could go and embrace her tightly. He listened to Davros's gleeful laughter and taunts and wished he could reach through the blue force field penning him in and put his fist through the rib cage of his cannibalized chest.
For an hour, they sat and knelt together and watched as the beam sped up and became wider spreading out all over the universe like a plague, destroying all life in its wake. He knew the same thing was happening in all realities. Untold numbers of people were disintegrating into dust without even knowing the reason why. He wished at this moment that Davros would just put him out of his misery so he wouldn't have to watch any longer. He could see his enemy's eye was on him, studying him intently, gauging his reaction but he no longer cared if he saw him or not as he became lost in his thoughts. He prayed that Davros would kill him quickly because he didn't have the hearts to go on after witnessing all this.
After four more hours of silent watching the destruction was finally complete and everyone wept as the twenty seven planets followed the rest of the universe and became nothing. Once that was done, Davros let out another insane cackle of triumph.
"AT LAST, I HAVE WON! I HAVE DESTROYED THE ENTIRE UNIVERSE!" he screamed as everyone stared at him with hate. "I HAVE TRIUMPHED OVER THE DOCTOR! I AND MY CHILDREN ARE NOW SUPREME! AHAHAHAHAHAHAHAHAHAHAHAHAHA…"
As the Doctor listened to him, he couldn't help but get in one final jab at his enemy before he was put to death.
"Yes," he said. "You're finally the master of everything except now there is nothing, so what are you and the Daleks gonna do with yourselves now?"
Davros's laughter died away when he suddenly realized that the Doctor was right. He was so busy making plans to destroy all of creation that he didn't stop to think what would come after it. The Doctor couldn't resist a smirk when he saw how quiet his adversary had become.
"A Dalek's purpose is to kill every living thing it sees and conquer the universe so what are you gonna do now that there's nothing to kill and conquer, huh?"
Davros started to speak but found he really couldn't answer the Doctor.
"Well, answer me, Davros? What are you gonna rule over when it's just you and the Daleks? If you put us all to death then that'll be it. Where are ya gonna live? On the ship? You'll have to since you destroyed every bloody planet in the whole of creation. You think you won but now you and your little pets are stuck on a ship in the middle of nowhere! As Donna over there would say, CONGRATULATIONS DUMBO, YOU ARE RULER OF ZIP, ZERO, ZILCH, NADA! How does it feel?"
The only sound in the room was the whirring of Davros's chair as he spun around to face the Doctor.
"Well, tell me how it feels, pruny boy. How do you like being trapped on your spaceship for all eternity with a bunch of Daleks who are basically useless since they'll have nothing to kill after they get done exterminating us?
Davros was speechless. As he stared at the Doctor, he heard Caan let out an insane giggle.
"Davros is an idiot!" he sang in a high-pitched voice. "An idiooooooooooooot."
Davros spun around.
"Silence. I will not be mocked!" he said, pointing at him.
"Daaaaaaavrooooooos is an idiooooooooooooooot!" Caan sang.
"Isn't that interesting? Turns out the insane Dalek is the sanest one out of you lot," the Doctor said.
Davros spun around and faced him.
"You may think you and your human companions are through with me, Doctor. But if we have to be trapped on this ship for all eternity then you will share our fate! You want to die and leave this existence? Then I will deny you and your friends that and increase your torment by keeping all of you enslaved for the rest of your lives!"
He looked at the Daleks who were guarding the captives.
"Take these prisoners down to the cell block. Divide them up and put them in cells so they won't be able to band together and escape."
"Escape where, exactly?" the Doctor said.
Davros ignored him. He looked at the humans who were not imprisoned in the holding cells.
"On your feet!" he barked at them. "You will obey or I will torture you all!"
The humans grudgingly got to their feet as Davros deactivated the holding cells. Immediately, two Daleks trained their guns on the Doctor and his clone.
"Take them away," he said to the Daleks.
The Doctor and his clone both glared at him as they walked off with the rest of the humans to their prison cells.
Once they were gone, Davros put his head in his hand.
"Oh crap. The Doctor's right. Now what do I do?" he muttered to himself.