Tick tock goes the clock
And what then shall we play?
Tick tock goes the clock
Now summer's gone away
Tick tock goes the clock
And all the years they fly
Tick tock and all too soon
Your love will surely die
Tick tock goes the clock
He cradled her and he rocked her
Tick tock goes the clock
'Till River kills the Doctor(Kovarian; DW6x12 Closing Time)
It's something of a farewell tour, he tells Craig. As he has told the others before that, whether or not they can hear him. This time around, he hadn't skipped the rewind, because this time he has had too many chances. Because this time, the universe will remember him, and rejoice or weep in turn.
He would prefer to be forgotten, he thinks, because at least there wouldn't be the knowledge that he's needed, and yet he's selfish enough to be going off and dying.
"Come on, old girl," he tells the TARDIS after he's left, "We've still got a little time for ourselves."
She had always been the last on his farewell tour, no matter that he'd done his best to make them all feel they were the last, the most important, because she is the only one left of everything he'd held dear. He lets her set her own coordinates - she'll take him where he needs to be, because she always has - and just watches. Waits. He doesn't know where he's going to end up, only that it'll be the last place that he needs to be before Lake Silencio.
When the TARDIS lands, he sets the hat Craig had given him on the console, heads out. He'd like to stay with her, but she'll have brought him here for a reason. She always does.
Outside, there is darkness. Darkness and rasping breaths, even when he holds his own breath. He can feel it in the dark, feel him, and he doesn't know how the TARDIS has done it, but she's certainly brought him where he needs to be.
"Master." He can barely get the word out, knows it's breathy and desperate and he can't even apologise - to himself, to the TARDIS, to anybody - because he is desperate. Waiting for a response, any response, and when the Master steps into view it doesn't matter that the other Time Lord is emaciated and dirty. It's the Master, and he's here and he's beautiful, no matter what he looks like.
"New face," the Master rasps out, staggers forward and falls into his arms. He touches at the Master's temples in ghosting movements, moves the Master's fingers to his own head and then it's all in their minds. No need for words; there has never been a need for words, only the fear of each other. There's no fear now, though.
He cannot kill the Master, because he has never been able to kill the Master and now wouldn't be the time to start. The Master cannot kill him, because he would know if it was the Master he was heading to. He always knows.
He is going to die, but the Master is not going to be the one to do it.
You're going to be last of the Time Lords soon. Breathy even though it's just a thought, all fear and love and something like jealousy and he hates that; he of all people shouldn't be jealous about someone else being last of the Time Lords. He's wondered what he'd be without the Master, seen it so many times and never known whether it's good or not, but he worries more about what the Master will be without him. Will you be as you were before? he wonders, All world-conquering and subjugation? Or will you-
There is no word outside of Gallifreyan for what he thinks next. No thought that can adequately express what it is that he means. Will the Master break? He can see the Master trying to destroy everything, trying to destroy himself. Or he can see the Master becoming him. Helping because there is nobody left to do it. Because there is nobody else and it's the only way to stave off death in any sort of meaningful way.
No matter that even in his mind he hasn't made it clear, the Master understands. Takes him, then, against the door of the TARDIS - because she was always going to be the last stop, and this way she still can be. The Master cannot come inside the TARDIS, not now, not so close to the end, but they can include her. The Master is slow and gentle and nothing like he has ever been before, because this is nothing like it has ever been before.
This is the end.
When it's over, there are no words, but both of them understand as he leaves, locks the Master out of the TARDIS. It doesn't matter how the Master got out of the time lock, that it probably involved things he doesn't want to hear about. It doesn't matter how he is going to die, or why, or even that he is.
It matters that this is the last stop, before it's all over. That prior to this he'd dropped off four letters to four very different places. That when it's all over, the TARDIS will return to the Master because they will be all that the other has left of him.
At Lake Silencio, the Doctor is ready, and prepares to face the Impossible Astronaut.