When Theta Sigma was a little boy --- not long after he'd been to the Untempered Schism and admitted to the Academy, in fact --- he and his friend were assigned the same tutor to help them learn physics. The tutor was very old when Theta first met her. She was in her thirteenth regeneration, and the oldest Time Lord that Theta had ever met. The tutor was very wise, and very stern, and she never let her two pupils play when there was work to be done and studying to do.
When they first met their tutor, whose name the Doctor cannot for the life of him remember right now, Theta and his friend were a little frightened of her. She looked so old and craggy, you see, and she was a little mean to them whenever they didn't finished assignments she gave them. As they came to know her better, though, they discovered she wasn't so very frightening after all. She was quite nice, actually, for such an old lady. Sometimes she gave each of them a sweet, and sometimes, when they had spare time after a lesson, she taught them old songs that no one else knew. When they studied very hard, she always patted their heads with her cold hands and told them they were good boys. When she smiled at them, which she always did whenever they got all the right answers on the quizzes she gave them, her gray eyes twinkled.
When they had learned enough to move up to the next level of their studies and didn't need a physics tutor anymore, their tutor told them that she was very proud of them. “But,” she told them, “I still expect both of you to apply yourselves to learning new things. Learning new things,” she explained, “is important because young Time Lords can always hope and dream, but you must keep learning and be willing to learn new things so that you will be able to accept things that happen in the universe.” Theta and his friend did not know quite what their tutor meant, but they liked learning so they thanked her for her advice.
A few years later, Theta and his friend, who was by now his best friend, were summoned to their old tutor's home. She was nearing the end of her last regeneration, and she had sent word that she wanted to see her old pupils one last time. So Theta and his best friend went to see her. They found her sitting up in bed, looking pale and very, very small. She was awake --- they could see she was awake from the way her hands moved on the blankets that covered her --- but her eyes were closed. When they said hello, she turned her head toward them but did not open her eyes.
“Boys,” she said, her eyes still closed, “I have one last thing to teach you. I know you remember the law of conservation of energy. I taught it to you, after all, and I taught you well. 'Energy cannot be created or destroyed. Energy can only be changed from one form to another.' You know that from your lessons, but it is one thing to know such a thing from a book or a lecture and quite another thing to see it happen. Now that I am dying, I can show you the law at work.
Although he'd long since stopped being afraid of his old tutor, Theta felt afraid at her words. “Don't say that. You're not dying,” he said. “You're just tired. We'll go now so you can rest. We'll come back tomorrow and see you. You'll feel better then.”
The tutor tilted her head and looked at Theta, although she kept her eyes closed, and smiled a tired little smile at him. Then, her eyes still closed, she turned her head toward Theta's best friend and asked, “Child, are you ready to learn a new thing?”
“Yes, I am,” he answered. “Learning new things is important. You told us so.”
“Yes, child, I did. And it's good that you remember. But you must also remember what I'm going to tell you now. Sometimes, a new thing is frightening, or painful, or simply more than you want to have to contend with. When you find that is so, you may spend time trying to disprove the new thing, and that is all right. Trying to disprove a new thing is a way of studying it. And studying it is important because, through study, you may be able to find a way to make the thing better. But, in the end, you must learn the new thing anyway, because that is the only way to be ready for the inevitable and unavoidable. Do you understand?”
“No,” said the Doctor's best friend, a puzzled frown on his face. “Please explain what you mean.”
“I cannot explain any better than I already have done, child, so I must show you instead.”
“Don't,” cried Theta, feeling even more frightened. “We'll come back tomorrow. You can explain then.”
“Theta Sigma, you are a good boy and a fine student, but you are not ready to learn this lesson. Someone else will teach it to you some other day. For now, please go sit in that chair,” Theta's old tutor ordered as she pointed a weak, tremulous hand at a chair near the door. Theta obeyed his old tutor. When he was seated, he looked over at her and saw that her eyes were still closed. She had not opened them once since he and his best friend came into the room.
“Now,” the tutor said to Theta's best friend, “come here, child. Sit beside me and look at me.”
Theta's best friend sat beside his old tutor and looked up at her face, which Theta could no longer see because his best friend's head was in the way. Suddenly, his best friend gasped. Then he stood up and backed away from the bed. When he did, Theta could see that their old tutor was very, very still.
“What is it? What happened?” Theta moved quickly to his friend's side.
“She's dead, Theta. She's dead, but she showed me...Oh, Thete! She put her hand on mine. And she opened her eyes and looked at me. She showed me.” His best friend's voice sounded very odd. He sounded excited and happy and frightened and sad all at once.
“What? What did she show you?”
“Energy changing. It was...I felt it. She was so hot. Her hands were never so hot when she used to pat us on the head. Remember how cold her hands used to feel? But she was burning up now. And I saw it. In her eyes. Remember how they were gray? They looked black now. They were black, but they had a sort of shine to them. Like a reflection. It was like...like looking at a piece of glass that's black but shiny like a mirror so that when you look at it you can see reflections. But, at the same time, I could see through to the other side of the mirror. I saw what was on the other side, and it was like...It looked like the universe. And it was...swirling.”
“That makes no sense. What do you mean, swirling?”
“I can't explain it any better than that, Thete. I'm sorry. But don't feel bad. She said someone will teach you one day. You'll understand someday.”
**********
Theta Sigma grew up, and graduated from the Academy --- well, barely scraped by on the third attempt, but he still graduated, thank you! --- and went on to do all the things that grown up Time Lords do. His best friend grew up, too, and became Theta's very best friend for a time. But then they fought, as grown ups sometimes do, and his very best friend did not stay his very best friend. Instead, he became the Doctor's best enemy. Sometimes the Doctor was sad about this. Sometimes, he was angry that his best enemy was so evil. Sometimes, but not very often, the Doctor was glad that his old very best friend was still a best something to him, even if it was a best enemy. Mostly, though, the Doctor did not think about it at all. There was so much to do and see, after all, and places and times to visit, and new people to travel with and so many new things to learn. Old best friends, even the very best ones, and old best enemies were old things, things he already knew, things he didn't want or need anymore.
**********
Time went by.
**********
The Doctor is old now, almost as old as his old physics tutor was when he first met her. He is so old that he no longer hopes for or dreams about anything; so old that he has learned many, many new things. He has learned how to kill, and how to lose everything, and to how be terribly, terribly alone. He thinks that he has learned all there is for him to learn.
But the Doctor goes on visiting new places and times, and meeting and traveling with new people, because he may be alone but he is still alive. Then, one day, he sees his best enemy. He is the same as he always was in some ways, but he has changed a great deal in others. He is more cruel than he ever was and delights in destruction more than he ever did. He hears loud noises that hurt his head and drive him to do all sorts of things and he cannot make them go away. The Doctor knows he can help him, though. The Doctor knows that if he is just patient with his best enemy and treats him with respect instead of always finding fault with him, he can make the noise go away. Then the Doctor's best enemy will be all better. And the Doctor will not be alone.
So, for a whole year, the Doctor is patient. He thinks of what he is doing as a game. A game where the goal is to keep secrets so well that his opponent never figures out any of the things he is trying to accomplish. He is quiet. He works on his plan to save the world whenever he is sure his best enemy is not watching. He never tells his best enemy how it is he will stop the noise. And he never, ever tells his best enemy how much he hopes that they will be very best friends again or how he dreams about how they will spend the rest of time together, just the two of them.
**********
Minor setback, the Doctor thinks as he catches the Master before he hits the ground. Maybe I can work on the drums while he's recuperating. Always look on the bright side. But maybe the Master's more injured than it first seems, because he's shaking and looking pale and talking about dying. The Doctor could do without the drama queen antics just now. It's only one little bullet. If the wound is really all that bad, the Master can “Just regenerate.”
The Doctor is more irritated than anything else when the Master says no. No one else is near enough to hear him. Why is he bothering to put on this show? But irritation turns to something else when the Master says “I refuse.” What can the Master be trying to accomplish? They played their game of cat-and-mouse, the Master lost, and now they can be with each other again. They can't rewrite the past, but they can script a new future. And they can do it together. That's what the Master wants, isn't it? Isn't that what they both want? To be together? “Please. Just regenerate. Come on.”
“And spend the rest of my life imprisoned with you?” The Doctor doesn't understand what the Master means. What prison? How can being together be like being imprisoned? When we had so much, when we can have it again, when we're all that's left, how can that be a prison?
The game is over but the Master is still playing and the Doctor does not understand why. Why is the Master still playing? Why doesn't he just stop this? It's not a game. Not anymore. No. No, no, no. This can't be. I cannot accept this. Not now. This is not how the game goes. This isn't even a game. Not anymore. “Regenerate!”
It's not until the Master says “I win” that the Doctor realizes that he and the Master are still playing games. Different games. For the last 365 days, they have been playing completely different games. They probably always have been.
There's nothing now. Well and truly nothing, the Doctor thinks. There are no more hopes and no more dreams. All there is now is the Master dying in his arms, and it makes him far from happy.
But that's wrong, the Doctor realizes. There is something else. There is still one thing he has to learn, and the Master has become his tutor. So the Doctor kneels on the cold, hard floor and looks down at the Master as he cradles him. He gives, finally, all of his attention to the Master. And he feels the heat radiate off his best enemy's body while he watches the universe swirl in his best friend's eyes.
