He isn´t sure who started it, but he feels as though he has played this game for all of his nine hundred years. That wasn´t true of course, because he remembers a bright eyed boy, laying next to him on the deep red grass, watching the stars. But maybe that was when it started. A game so complex and yet so simple.
The only way to win was to make the other let you win, but letting the other win meant to give up, to surrender. Something neither of them would ever do. And so it continued.
They fought, with the Master making his plans, waiting for the Doctor to show up and stop him. There were small victories sometimes, but even if the Master´s plan was ruined, the Doctor still had not won, because when they were alone later, they would smile, eager for the next round to start.
Most companions of the Doctor noticed how excited he seemed to get whenever he came across one of the Master´s schemes. And the Master found himself deliberately leaving clues, because what fun was taking over the world if the Doctor wasn´t there to try and stop it?
And then he did conquer the world, and the Doctor wasn't able to stop him. It soon got boring though, because he hadn't won yet, and the Doctor wasn't doing anything. He hadn't surrendered, but he didn't seem to be fighting either. So he tried to get him to take action again, to fight, and if that wasn't possible, then to make him surrender.
When the Doctor's companion finally came back, he was happy, because the Doctor had been fighting back all along, and as time erased his crimes, he couldn't help but appreciate having such a worthy opponent.
"I win" He had said that day, because although he was the one dying, he could see the defeat in the other Timelord's eyes. But he had spoken too soon, and a year later, the dark was banished by an explosion of light and he could feel the power swirling around him, reminding him of the vortex. He was alive again, broken en brought back wrong, but alive nevertheless. It was during what the humans called Christmas, in the deserted wastelands that he smelled him and the next round of their game started.
And so they continued their game, although they both realized they were getting tired. There were moments where they were so close to letting the other win, only to realize that meant they had to surrender, and neither of them was willing to give up like that.
The Master knew that taking over the world wasn't what he wanted really, but it was a habit, and he knew the Doctor would stop him anyway. He was tired of this, but anything else would mean a surrender.
The Doctor knew that all, but he also knew that he could never let the Master win. They were trapped, both of them, trapped in a game they knew would have no winner in the end, because no matter how much they wanted not to lose, neither really wanted to win either.
Their solution came in the shape of an old service revolver and a white-point star diamond. Time itself seemed to stand still as the Lord of Time aimed his gun at his friend and rival.
When he whispered "Get out of the way" it had a much deeper meaning, and a small smile appeared on the other Timelord's face as he figured it out.
The bitter " I know" only confirmed what he had already read in his friends eyes. The Doctor had surrendered, the games seemed finally over. The Master shivered slightly as he realized what that meant: he could do whatever he wanted.
"Get out of the way," He echoed.
For one small moment their eyes met, but it was enough for them to understand. They would both surrender, the Doctor in letting the Master go, even though he would not be able to stop him again, and the Master, by abandoning his habit of trying to kill, instead saving his friend.
The game, the endless fight, had ended in a draw. The next time they met, they might start a new game, but for now they were free to act as they liked, and so the Master surrendered.