850 words, teen and up, not mine. After leaving Amy's room, the Doctor finds himself in a time and place he never expected.
WARNING: includes Crispy!Master's medical issues.
He slips through the crack in Amelia's wall and finds himself in the control room of a TARDIS that isn't his.
The desktop is set to glossy black, and there is a set of file cabinets against one wall. That tells him everything he needs to know; he's in the Master's TARDIS.
He shouldn't be here, and he's about to turn back, when he hears a far-off sound, halfway between a sob and a moan. He hurries toward the sound, lowers his mental shields and then he feels the pain. He slams his walls up and finds himself sprawled on the floor, breathing hard.
He shouldn't be here, but neither can he simply turn his back on someone in that much pain.
He follows the low cries to the sick bay and for a moment he can only stand, aghast, at what he sees.
He would never have recognized the Master if he hadn't seen him like this, on Gallifrey, on Traken. His skin has sloughed off in sheets, and he's leaking, and yet he's still on his feet and when the Doctor realizes what that means, he feels his stomach turn over.
The Master may still be standing, but he shows no sign that he's aware of the Doctor's presence. Every fiber of his being is focused on the task of staying on his feet, of minimizing his contact with any surface, of delaying the inevitable moment when he'll collapse, and the pain will rocket from merely agonizing to unbearable.
This has to happen. It's already happened. Interfering would cause a paradox, worse, it might undo his efforts to reboot the universe. But even as he's thinking this, he's already reaching out, touching his fingers to the Master's temples as lightly as he can, though even that causes him to flinch back and for a moment, his moan sharpens to a wail.
It's frighteningly easy to push into the Master's mind; his defenses are as shredded as his skin. There's no time for subtlety; he presses here and here to alter the Master's brain chemistry directly, releasing a massive flood of natural painkillers.
The Master's disfigured face goes slack, and he slumps back against the wall before sliding toward the deck. The Doctor catches him and eases him gently down. "There," he whispers. "That's better. Isn't it?"
There's no answer; what little consciousness the Master managed to cling to is already fading. His eyes are unfocused and if he had eyelids --
The Doctor rakes his hands through his hair, feeling helpless. He should leave, he knows. But he also knows that in a few hours, what he's done will wear off and the Master will wake to the same torment.
Knowing what lies ahead for the Master, it would be kinder to kill him now. He could do it easily, with no pain; just slip back into his mind and depress his cardiovascular system until the point where his hearts stop beating. He probably wouldn't even feel it.
But killing the Master would irreparably damage the timeline.
It might just be possible, though, to slip a little comfort through the cracks. To make the Master's wait for Chancellor Goth a little less painful.
He leaves the Master where he is; there's no point to moving him if he doesn't have to. Once he's convinced the Master's TARDIS that he's trying to help, it doesn't take him long to find what he needs; a few spare panels and a gravity projector. He uses the panels to fashion a pod, big enough for the Master to rest in, and sets the tiny captive gravity well so that the Master will float without touching the sides.
After that, it's the work of a few micro-spans to program a topical numbing agent into the medical dispenser. He leaves the information on the screen, then takes the resulting ointment and slathers it on the Master's skin before settling him in the pod. Weightless, his body is limp. But his lidless eyes still seem to be staring. The sick bay's bright lights will only make it harder for him to sleep.
The Doctor knows he's pushing things, but he can spend a few more minutes. He activates the TARDIS's voice interface and is surprised to see his younger self standing there, looking like he did when he was at the Academy.
He ignores the implications; the only thing that matters is that the Master will be able to control his TARDIS without leaving the pod.
He's done everything he can, but still he hates to leave the Master to suffer. But he knows he's already stayed too long. He dips into the Master's mind one last time, to release another flood of chemicals, enough for him to sleep for a few hours. Impulsively, he bends over to ghost a kiss a micron above the Master's forehead. Then he dims the lights to let the him rest as comfortably as he can.
The last thing he does before he leaves is to erase any trace of his presence. Then he slips back out the way he came, though the crack in the universe.