Anakin Skywalker, or Darth Vader as he was then known, was almost finished with his purge of the Jedi Temple. Nobody that he had come across had put up much of a fight... against the power of the Dark Side, all would eventually fall. There was only one Jedi Knight who had evaded him, but wouldn't for much longer.
Ahsoka Tano, his former Padawan, now an enemy to both him and the Republic. He would show no mercy.
After dismissing the clones, he ignited his Lightsaber and very slowly walked through the halls.
"Come on out, Snips. If you do so, then I'll make it quick and painless, unlike most of the traitors I've fought here today. It's the least I can do for you after all we've been through together."
Clap, clap, clap.
His target had indeed came out of a side room, of which he was sure that he'd sweeped earlier and found nobody within. Clearly, she was able to hide her Force-Signature, but that wouldn't save her from his wrath. She was smiling and clapping, and stopped a small distance away to face him.
"Well done, Master!" she hissed, emphasizing the last word with pure venom. "You've finally given in to the Dark Side! Not because you had a good reason, oh no... but because you think she is going to die. You betrayed everyone for her, but most of all you betrayed me."
"Don't you dare speak another word against her! For that, my promise of making your death quick and painless is rescinded. Prepare to die, Ahsoka."
"You're the one that's going to die here today, Vader." said Ahsoka. Her blue eyes had immediately taken on a sickly golden glow, and her normally vibrant skin paled. "I've been wanting to do this for a long, long time. You really have no idea, Skyguy!"
Moving faster than he had ever seen, she ignited both of her Lightsabers and rushed for him. Surprisingly, she was holding her own against him, and he had to fight hard to block and parry her attacks, many of which would have been fatal had they connected.
She was fully immersed in the Dark Side of the Force, and judging by her power, for a very long time. How did she hide it from the Jedi Council, or from him for that matter? It didn't make any sense!
"I can read your thoughts, you know. You wear your emotions on your sleeve for anyone who has the eyes to see them, don't ever underestimate the power of the Dark Side. It lets me do many, many things, and I'm going to use it for the good of all. Not like you or your new Sith Master!"
Vader was genuinely shocked. Of all the Jedi he had ever known, Ahsoka Tano was absolutely last on his last of those who he thought could turn to the Dark Side. He had expected her to make a short speech about how he had thrown everything away, before swiftly ending her life. Instead, he was fighting for his own very life, and she fully intended on killing him. He couldn't fail Padme, not after everything he had done that day.
He went on the offensive, looking for an opportunity for a quick kill. He managed to knock her left-handed Lightsaber away, destroying it in the process, but she quickly recovered and continued the duel. It was a stalemate, Dark versus Dark... the battle went on for several minutes, with neither doing any significant damage to the other.
"Enough of this." said Ahsoka, who after dodging a swipe that would have decapitated her, fired Force Lightning from her free hand point-blank into his chest. He fell to the floor, spasming and screaming in dire pain. She continued her assault for about a minute, grinning and cackling all the while. Ahsoka then sheathed her Lightsaber and took Vader's own away, and sat down on the floor next to him.
Vader was so badly damaged by her onslaught of electricity that he could not move any part of his body except for his head and was too weak to even attempt to use the Force, not that Ahsoka would have let him if he'd tried.
"Before I kill you, at least you'll know how I ended up this way. This day already happened to me once before, a very long time ago. I was just a naive Jedi Knight, no different from any other, when you came in here and started killing everyone. I didn't even get out so much as three words before you drove your Lightsaber through my stomach. I still have a horrible scar there that I'll have the rest of my life, you know... somehow it managed to come back with me. Anyway, I just barely survived, but nobody noticed. You just assumed I was dead, you thought absolutely nothing of me. You were my Master! I would have followed you anywhere you decided to go, even down the path of the Dark Side together, but you didn't so much as give me a choice. Just as I was nothing to you, you're nothing to me now. Absolutely nothing."
She paused for several moments, tears trickling down her cheeks, whose color had returned to normal along with her eyes.
"I ran far, far away. You were my best friend, and I had nobody left. Even though I hated it at first, because it went against everything I was ever taught, the Dark Side was all that kept me alive all of those years. I killed any agents of the Empire that were unlucky enough to stumble on me, but even then you couldn't take the time to come after me yourself. You were either a coward, or figured that it couldn't possibly have been me because I was so weak. You trained me, so what does that say about you, huh? My hate for you took over and made me strong, but after years of honing my skills I still knew that I was no match for you. But by that time, I'd heard that you had died anyway, taking away any chance for revenge. It took me the better part of a decade and the power of two suns to be able to go back in time to when you were weak and pathetic as you are now, but apparently the Force didn't want me to stop Order 66 for some reason and instead just brought me right here, into my younger self."
Ahsoka stood up slowly, and ignited her Lightsaber once more and pointed it directly at Vader's heart. "Goodbye, Sky-"
She was cut short by a Clonetrooper's blaster from behind.
There had been so much noise within the Temple, in particular Vader's screams of agony, that most of the Clonetroopers outside and around the Temple heard. Ahsoka had been so bent on revenge that she had failed to anticipate them, and by prolonging Vader's suffering instead of just killing him, had sealed her own fate.
Ahsoka was yet another victim who thought she could control the Dark Side, when in reality it controlled her. It chewed the Togruta up and spat her out, as it had done to so many others who were foolish enough to believe its promises. As for Vader, though his injuries were severe, it was nothing that a few hours in Bacta didn't fix. His new Master needed him to go to Mustafar, after all.
As for his former Padawan, her body was thrown into one of many burning heaps of Jedi corpses, and forgotten.