"I had a friend once. We ran together when I was little. And I thought we were the same. But when we grew up, we weren't." - The Doctor, Death in Heaven
"I need you to know we're not so different. I need my friend back!" - The Mistress, Death in Heaven
"No!" the Master howled, struggling against the grip of his guards and the restraints. "No! No! You don't understand! Stop him!"
The Time Lords hadn't been certain what to do with the Master. They'd stabilized his failing body and extracted the thundering drums from his mind, then locked him away. It was a nice prison, because they felt guilty, because it was possible they'd made him insane, but a prison all the same. Some called for his execution for murdering Rassilon. Others said it had been justified, particularly as Rassilon had been about to destroy the universe. (They conveniently did not mention their own complicity in that matter.) And they locked him up until they could decide what to do with him.
The greater debate raging across Gallifrey was what to do with the Doctor when he returned to them. He had killed them all; every Time Lord remembered dying in agony in the Doctor's genocidal inferno. And then, after they were dead, the Doctor violated all of Gallifrey's temporal laws and undid his terrible deed, and saved them by locking the planet away in this dark universe.
The fix had been imperfect. Gallifrey was slowly dying, hidden away without its sun to warm it. Without the stars in the sky, without the Eye of Harmony, the Untempered Schism, the Time Vortex, they waited. And, of course, the DOctor, who had saved them from the Daleks and from themselves, was their only hope for rescue from the darkness. As such, there had been no debate at all when it became necessary to reach through the crack and bestow a new regeneration cycle into the dying rebel. Self-serving decisions were always the easiest. The Time Lords would let him come and rescue them, as he inevitably would. But after ... what were they to do with such a man? He frightened them as much as he inspired them, and the populace was divided on whether, upon his return, they should kill him or make him king.
Suffice it to say that the question of what to do with the Master was not a priority. So they chained him, and guarded him, and they all waited.
Four bangs on the door snapped the Master from his meditation. The guards did it on purpose; they liked to watch him flinch. "Come with us now," they commanded, holding up a scarlet robe. The robe was the most formal of all Time Lord garments, its cuffs and collar proclaiming all his names, the garb of the high solemn assembly of the Time Lords. All were required; the Master could not be excluded from such a gathering.
"The Doctor is here," the Master deduced triumphantly, as his sullen and lowly Gallifreyan guards helped him into the robe. To embarrass him, they chained his feet and led him to the Great Hall. Above him, the vast glass dome had been repaired. There was no point to it, though. The sky was black, empty and dark forever.
"My family seat is at the front," the Master instructed.
"You'll sit in the back," one of the guards sneered.
They led him up, up, high above the dais. The Master did not sit, but leaned forward, his hands spread on the balustrade, needing to be as close as possible. Far below him, the Doctor stood alone, with a new face the Master had never seen. He was dressed simply, dark coat and trousers in the style of Earth, rather than the robes required of the setting. Beside him were two boxes: the ridiculous blue of his ancient Tardis, and the clockwork gold of another machine.
"The Moment!" the Master whispered to himself, his guts twisting with unease. "I knew he still had it somewhere."
The chamber went still; it had apparently been called to order.
"Time Lord," a voice said, intoning formally. The Master could barely hear it, but he thought it might be Romana. "What is your name?"
"I am Nameless," the Doctor answered, his voice clear in the silence.
The Master breathed in shock; around him, the Time Lords did the same. To renounce the names of family, of clan and order and caste, was a condemnation of Gallifrey; a refusal to be associated with their evils and abominations. On the other hand, to forsake one's chosen title was the confession of a criminal, who, in guilt, would not sully the hallowed halls with the sound of his name. Nameless, the Doctor had declared, and the Master's instincts screamed with indecipherable warnings.
"I need to get closer," the Master whispered urgently to his guards. "I must hear!" They were unmoved by his plea. He pounded the rail in frustration, then returned his attention to the proceedings, looking down as his oldest friend and best enemy paced below him, shining in the midst of those who would dare to presume to judge him. The Moment had been activated, its interface in the form of a young human woman. She and the Doctor were speaking, and for all their pomp, the assembled Time Lords were ignored and unimportant.
The Master could barely hear the Doctor, but he did not have to, because with sudden, sickening realization, the equations flickered through the Master's head. What power was sufficient to return Gallifrey to the living world? The answer was laughably simple: the energy from the lives of one Tardis, one living weapon, and one Time Lord with a full regeneration cycle.
"No!" the Master howled, understanding long before the staid dim-wits of Gallifrey. "No, no!" He twisted from the grip of his guards in time to hear the Moment say:
"...life freely given?"
"Given," the Doctor answered, his head bowed.
The Master's scream of despair mingled with the Doctor's cry of agony as the room crackled with light, streaming dangerously from Time Lord to Moment to Tardis. Heedless of his chains, the Master ran, down, down, bursting onto the dais and falling to his knees beside his prostrate enemy of old. The dying Doctor focused on the Master slowly, by degrees, fighting through the torture of being unmade to smile faintly at his friend.
"They are not worth it!" the Master raged, cried, straining through the the thick light for the Doctor's hand. "You fool, they are not worth it! Billions of them are not worth one of you."
"Billions of them," the Doctor said hoarsely, "and you. A good trade."
Someone kicked the Master, hard, rolling him away from the Doctor. "Don't touch him," she said sharply. He looked up in fury at the Time Lady, who had abruptly materialized on the dais dressed in Earth's finest Victorian garb, and recognized himself.
"Stop him!" the Master-of-the-past begged the Mistress-of-the-future. "Stop him!"
"I tried," she said, her voice rough with sadness and despair.
The Doctor gasped in pain, near his end, burning in the light. The Moment's form knelt beside him. Her hand was on his shoulder, and she flickered from face to face, many of which the Master recognized as the Doctor's companions of old, and whispered comfort to him in their voices. The Tardis's cloister bell tolled mournfully, breathlessly, as she died alongside her beloved thief.
The Time Lord council, frozen in impotent shock, was suddenly dazzled as sunlight burst through the crystal dome for the first time since the end of the Time War. The sun rolled wildly across the heavens while Gallifrey twisted back into the universe, then settled on the horizon as the planet righted its orbit. The Doctor tilted his head to feel it's warmth, his hands clutching at the ground.
The Master surged forward and pulled his friend into his arms, rocking him to his death as the Doctor had once done for him. The Mistress did not stop her younger self this time, and the Master welcomed the familiar taste of blood on his lips as the terrible energy still surging through the Doctor burst the Master's internal organs.
"It's dawn, Koschei," the Doctor whispered, eyes unseeing, and died, his wild timeline cracking through the air like ice on a mirror, leaving the Master's arms empty. The Mistress closed her eyes and lifted her face to the sun, her tears graving lines through her painted face. The Doctor's Tardis moaned in agony, then folded the last of him into herself, before vanishing silently to perform her last devotion.
The Master collapsed backward, and felt regeneration beginning to take him. He looked up at the Mistress, who was looking down at him in distain. "He died on Gallifrey," the Master whispered. "The Matrix ..."
"He isn't there," the Mistress said, something like pity in her voice.
"I'll stop him," the Master hissed up at his future self. "I'll go back in his timeline and stop him. I'll turn him into me, because I would never die for Gallifrey. I'll corrupt him. I'll change him. I'll save him."
The Mistress knelt beside her past self. "You really won't," she hissed viciously into the Master's ear. "I have one more exit line, love," she said, grinning manically. He watched as she stood and turned scornfully to the shocked Time Lords. "He was not yours! He was not ever yours!" she spat at them, then pressed a device to her neck and vanished. The Master gasped his last breath in this body as he felt the echo of her disintegration, the future destruction of his soul in permanent, self-inflicted death.
But he would not think of it. He felt himself regenerate, and the ideas swirl in a new brain. First, she thought, I'll try building him a Cyberman army.
Notes: What if Missy is from the Doctor's relative future? And what if everything she does, from Clara to the Cybermen to lying about Gallifrey and more, is to try to save him, in her own twisted way?