He flees because he's terrified, because he's small and lonely and looking at that empty endlessness, he faces himself.
Meanwhile, the boy just behind him in line can barely be pulled away from the darkness; and the tearing his mind undergoes is deafened by the roaring of drumbeats in his ears.
-----
"Come ON, Theta!"
Theta struggles under the stack of books he carries, his gasps of pain and anguish punctuated by his pleas for help.
Koschei doesn't aid him, doesn't move to save him. Theta can manage. He pauses to let the smaller boy catch up, chuckles and clucks at him, always trying to carry something that is bigger than himself.
-----
Koschei doesn't let Theta know he hears him crying at night. He never moves to comfort, or shift to hold him, doesn't stretch across the gap to touch and caress and soothe.
Theta cries for the parents who never loved him, for the family who's thrown him away to the Academy and never comes to see him. Theta weeps for the friends that he will never lay eyes on again.
Theta sobs endlessly into his pillow, and some part of Koschei is gratified by those tears.
-----
"Tell me. You like it."
Silence.
He thrusts deep in one move. Theta's aggrieved groan is buried in the duvet.
"The-TA," he says, getting more forceful with every thrust, blithely ignoring the whimpers of pain Theta's desperately trying to swallow. "Tell. Me. You. Like. It."
But Theta, barely coherent beneath him, feebly shakes his head.
Koschei doesn't mind. He likes Theta's spirit, likes this resistance to his domination. He knows Theta loves his rough handling, craves it like air.
His vision whites out, and when he pulls back, he sees the red spots dripped on the sheets and he's secretly pleased.
-----
They stare each other down, a century later. Gaps are forming beneath their feet; gaps that signify this planet is going to fall apart beneath them.
Even powerful young Time Lords as they are, neither one is stopping it. The Master started this mess and the Doctor is not here to fix the problem. He knows already it's too late to save this population.
They will be the Master's first victims. They will be the Doctor's first martyrs.
They're standing ten feet apart but it might as well be miles. The Doctor is screaming at him across the widening crevasses, trying to get the Master to listen to him, just this once.
Please, Koschei. I love you. I forgive you. Just listen. Come back to me.
But the Master no longer cares to listen, no longer wants to hear the Doctor's pleas to come home. To redeem himself. He isn't Koschei anymore; that boy is dead and gone.
The ground beneath their feet suddenly gives way, and both of them are sent plunging into a deep crack so many feet deep...
-----
One thing the Master can always count on, no matter what body each happens to be on when they run into each other, is the Doctor's pathetic penchant of forgiving him when he causes havoc, destruction, and general mayhem.
Just one time he wishes the Doctor would get over himself and just kill him.
Maybe it's the wanting to be equals; to be on the same wavelength again and not have to chase after the sunbeam that the Doctor always seems to want to ride.
The Master hates sunbeams. They give him a migraine.
-----
He thinks he's long past regretting the Master, but every time they clash he remembers what things used to be like, between Koschei and Theta, and he shudders at the memory, the cool lips on his neck and the body tearing into his.
There was pain, always pain, but pain was Koschei's lover long before Theta was. Some part of him wants to return to that, giving himself away again, young and stupid and not realizing what he's not getting in return.
-----
"No."
"No?"
"I won't fight you this time. You're on your own." He turns and steps one step.
"You fucking coward."
His back stiffens slightly at the expletive but he keeps on walking. He knows the Master can't help but bait him. Make him meet his eyes.
"You're running away again."
The Doctor turns and just looks at him, his face a picture of grief, and the Master feels something intangible break.
When the Doctor speaks again, his voice is strangled.
"I'm not."
The Master watches him walk away across the sand towards his TARDIS, and some part of him is angry that the Doctor has finally found the strength to walk the other way this time instead of running.
-----
"You must have felt so powerful."
Silence.
"Like a god."
Still silence.
He kneels down next to the prone form.
"You must have felt...invincible," he whispers with his mouth near the Doctor's ear, getting the gratification of seeing him flinch away from his touch.
"Tell me how."
The Doctor's big brown eyes turn on him, confused.
"How what?"
"How you survived."
The Doctor rolls away from him, exposing his back, but not before the Master sees the look of disgust written on his ragged features.
"Come on. You can tell me."
He barely hears the reply. "No."
"Come on...Theta," he says, a slight whine to his voice. "Tell me."
Despite his aged body, the Doctor proves remarkably agile in this moment, standing and practically running away to the other side of the Valiant boardroom, the huge table between them.
"Oh, come on, Theta Sigma. You KNOW," he coos as he stalks towards him, trying to warm the suddenly chilly atmosphere.
The Doctor shakes his withered head, refusing to make eye contact, and the Master is forcefully reminded of that scrawny fool who carried all those books from the library.
The Master chases him, pinions the Doctor's thin, shaky frame to the table, feeling every jut of bone beneath the dirty pinstripes.
Like a butterfly with torn wings, or a moth to the flame, the Master thinks as he ghosts his lips over the curve of that neck.
The Doctor shudders beneath him, his breath catching slightly.
"Remember what I used to do to you?" the Master whispers softly.
-----
The funeral pyre bursts into scarlet and orange.
As what little remained of his world burns, the Doctor finds the strength to walk away and not look back.