She was right, it had hurt. But without Ohila's elixir, the Doctor could not have lived. Now, light and energy were streaming from his hands and face as every cell in his body burnt and was reborn. The pain was unbearable, but necessary.

Eventually the burning stopped. The light faded from his body and the Doctor fell to his knees. Regeneration was always exhausting, even if he was a veteran by now. This was his seventh, but it felt different this time. Perhaps because he was already dead when it happened, the result of a crash landing.

Perhaps also because, this time, he would not just have a new body, but a new mission. No longer could he be the Doctor, whizzing around planets, dazzling young companions and himself feeling young in their presence, and saving people from monsters. Neither could he be the Doctor who stood by in the Time War.

He rose from his knees and began to get a sense of his bearings. His crash onto the planet Karn hadn't happened even twenty minutes ago, so he hadn't really had time to check out the place. He had woken in some kind of temple, with a stone altar, and a pool of reflection. Candles were neatly strewn about the place, giving the place a warm light it did not deserve. Particularly with a body on the altar.

"Is it done?" he heard Ohila ask from outside. She and her sisters had left him alone for the regeneration. It was a little surprising she waited. As head of the Sisterhood of Karn, she was accustomed to things running on her schedule, rather than anyone else's. Still, as the one who prepared the elixir, she wanted to know if it worked. Those keepers of the flame of eternal life were precious about their standards. But he wasn't ready for her yet. He needed to know more about this new self.

He held up his hands. They were young. He put one to his chin, realising he was clean-shaven. A reflection in the pool showed him his face was too. He had much too much hair, like the last time. That would have to go. It was dark brown again - he might have kept it long, had it been ginger, but not brown. Thin but pleasant eyes, that bore none of the weight they would.

But it didn't really matter what he looked like, the Doctor reflected. He would not be staying long in this body. Ohila had asked if he wanted to be fat or thin, young or old, man or woman. She was generous like that. But his only request was to be made a Warrior. After all, the universe had no more use for a Doctor.

"Doctor no more," he uttered. His voice was raspier than his young hands and full hair suggested.

Ohila took that as a sign that she could approach without invitation.

"Thank you, Doctor." He winced at the name, but she ignored the reaction. "But there is no time to spare. The universe remains on the brink. You must intervene"

His hearts sank at his new mission. It would take some getting used to: end the Time War.

The War had now raged across millennia and threatened to tear apart the universe. It began simply – the Daleks and the Time Lords, and it was easy to tell who was good and bad. The Daleks – mutants placed in an armed metal shell whose only desire was to destroy anyone and anything different. The Time Lords – well, on a good day they were a pompous and pretentious people with a penchant for silly hats. On their best days, they were full of intellect and wonder, and consumed by an endless quest for knowledge and justice.

But those kinds of days were over. The Time Lords could claim no moral high ground as they devoted their intellect to warfare, and tolerated the deaths of millions in the crossfire.

Cass knew this. The Doctor looked at her, lying peaceful on the altar. This should not have been her future. He ran a hand over her cold body.

Not half an hour ago, his old self had heard her call for help from her disintegrating ship, as it sped out of control towards Karn. Now both of them were gone. He had rarely seen such courage. After explosions had rocked her ship, she had teleported all her crewmates off and taken over the controls. She hadn't even been the pilot, but just transport crew. She must have known there was barely any chance of survival.

He had been her last chance, and had relished it. He felt a sting in his chest, as he remembered. As he led her towards his ship, bantering with her about the adventures enjoyed by companions of the Doctor, he had daydreamed about the capers they might have got up to.

Regardless of the other Time Lords, this is who the Doctor was. He found people in need, and saved them. And sometimes he found someone he wanted to travel with. They had to be bright and energetic, but above all needed a sense of justice. Cass was all of that. But to her, he was just another murderous, warmongering Time Lord. She rejected him, and they crashed on Karn together.

Ohila observed the weight increasing in the Doctor's eyes. "Let her be the War's last casualty-"

The Doctor cut her off. "I fear there will be many more," he retorted, before turning to look her in the eye. "But the Doctor will be the last."

"Then your mission awaits, Doctor."

He looked away, and stayed rooted to the spot.

"Where do I begin." It was less a question than a sigh. "I was the Doctor. I helped people. It was never my wish to harm."

He turned back to her. "I was the Doctor so long, I don't know how to be anything else."

Ohila understood that this Time Lord needed a push. She mused quietly, "she had a family, you know." The Doctor's head fell. "Back on Raxon. Her home planet. I can see it. A place of fire and mountains, with a bitter winter."

"Her parents. Freya and Shan. A carpenter and a pilot."

The Doctor's discomfort was plain. "They must have said their goodbyes when she joined the transporter."

Ohila played her trump card. "Also…a sister. Who is still on Raxon."

Acceptance, though not exactly joy, washed over the Doctor's face. He would give Cass a proper resting place, and then join the War. He snapped Cass' bandolier off her body, putting it on himself.

His new voice sounded strong for the first time. "Have you sisters prepare her and bring her to my TARDIS." Ohila bowed her head slightly, masking her dislike for receiving orders rather than requests.

"And Ohila – I'll need directions to Raxon. You may need to input them yourself, as I haven't the foggiest how to fly her."