The Vampires of the TARDIS (The Vampire Diaries/Doctor Who Crossover)

Regeneration

"I don't get it" Chronos muttered, "Bad Wolf was a god in that body, how on Earth did you kill her?".

"Kill her?" Mikael replied, "No, no, no... I didn't kill her, I destroyed her." He pulled the dagger back out of its sheath, "This was fastened from the strongest form of magic on this planet, it ripped apart her very being, and disintegrated her energy, you should thank me boy, now she cannot bother you with her ramblings of War and... and.... Dalinks?"

"Daleks", Artemis was up. "And for your information Mikael, the Daleks are going to destroy this entire universe if we can't get back to our planet, which you have just cemented given that our only means of returning just exploded into dust by your blade."

Before he could respond, the rest of the Mikaelson family had begun to stir.
"Leave here, before my children awaken properly. I only did what I did because they were in danger from your friend. I owe you nothing. SO LEAVE!", the last words said with surprising ferocity. Chronos turned to Artemis, she nodded at him, she knew exactly what he was thinking. Chronos turned back to Mikael, and in one swift movement, ran toward him and threw him across the room. The anger at the fact that they were now trapped on this planet had boiled to the surface, there was no way that they could get back to Gallifrey and stop the Time War. Artemis followed in her brother's actions, swiftly moving next to Mikael, kicking him into the wall of the small dwelling in which they were. Mikael stood up.

"This is the thanks I get for turning you into gods? You ungrateful little brats! I TOLD YOU TO LEAVE! GO NOW BEFORE I MAKE YOU REGRET IT!"

"In case you haven't noticed Mikael, the two of us are the one's with the enhanced abilities, and you just cemented our planet's, and indeed the whole Universe's, demise." Artemis retorted. She made another move toward him, but this time he was too quick. He unsheathed his glowing dagger and thrust it into her right heart, the Time-Lord heart. Artemis fell backward and began to glow a bright orange. Chronos knew what was about to happen, he used his newly-founded speed to grab his sister and race out the hut, back into the clearing in which they had first arrived on Earth. 

Artemis dropped to the ground, panting heavily. "Get back Chronos, you know how dangerous this process can be, and we have no idea what could happen with the Vampirism thrown into the mix."

Chronos stood back. Artemis pulled herself up off the ground and spread her arms out wide, the wound in her chest wasn't healing like it had last time, clearly the magic in Mikael's dagger countered their new abilities. But there's one thing that would be impossible for it to prevent, the aspect of Time-Lord biology that gave them such an advantage over other lifeforms;

Regeneration.