A/N: The whole fic is very cerebral. It is up to you how metaphorically or literally you choose to take it.
The Doctor has not always been blue—rather, he has crossed the spectrum as he crossed the generations. He has been gold, and burgundy—he has been so red with anger and pain that his own inner pyre was a certain sort of beautiful. The Doctor has been many things—the Doctor still has things to be.
The sick thing about this blue, is that it has a life all its own. It is never one single thing. Often it is bright, electric—buzzing with that vibrance and life the Doctor does so well. It goes murky in a snap—often at the sight of his precious humans in pain. But almost always, it is cool and liquid. This Doctor pours across the universe and he heals.
A true doctor, this blue.
And those blasted smiles of his just crackle with it; blue surges out from him in a glow. He leaves iridescent fingerprints on the shoulders and arms and backs of each life he comes into contact with—sticky residue that can't be washed off.
And heaven knows he's tried.
It's the fingerprints that nag at him. They taunt him from the relative safety of his reflection—smirking out at him with their opal sheen that shimmers the Doctor and flickers from view.
The amount of bathroom mirrors he's lost to the damn spots surely borders record-breaking.
They look wrong. They stand out against him too strong. Too... alien.
The Master fancies himself brown, this time around. A warm brown—a mahogany, maybe. Or even a maroon. While he's always had a taste for red, he thinks himself more subtle than that.
Those damn blue fingerprints don't look good on brown. They glint out with the gaudy presumptuousness of sequins and stain most of his best suits and all of his good ties. They haunt his jaws like five o'clock shadow and paint blue-tinged streaks into his hair.
He's turning utterly blue and—damn it, he's brown. Mahogany. Professional. Not this playful, childish, uncapped highlighter hue.
It's something that bothers him only after he steps outside of the TARDIS.
Inside, there are other things to do.
The Doctor's hands are on him—leaving dirty blue streaks up and down his arms. His mouth draws constellations in the prints on his face, stopping last at his lips to pollinate the blue against his tongue.
The Master remembers that he is supposed to be annoyed. Opening his mouth for complaining invites another investigation into the contents of his jaws and the Master forgets again.
The blue seeps from the Doctor's skin, dusting the Master's fingers when he draws them over the Doctor's neck—rouging his lips when the hands are replaced by his mouth to suckle and kiss and bite the pale tinge away.
The Doctor's hands drag across the Master's shoulders—pulling him in tighter, painting thick blue lines over one of the last suits the Master owns that is—was—left unmaimed.
The Master lifts his attentions to that mouth again—the bluest of it all. He claims it, with a hungry attack that sends spatters of blue whirling across the lower half of his face. The end of his nose is buried by the Doctor's cerulean residue. The kiss is all tongue and teeth, the Master taking his own revenge for the hand prints emblazoned on his skin.
The Doctor sits back, that electric blue smile buzzing to life on his lips yet again. "Look what you've done to me," he says.
Dusty brown patterns weave stains across the Doctor's face.