About a month later the Doctor tracks him down to ask about Gallifrey and the Timeless Child. The Master has no intention of telling her anything, which makes her fist her hands and shout. The Doctor's anger is a wonderful thing to behold, and her oldest enemy is one of the few it doesn't work on. He lets her rage, and she swears at him in a dozen languages before starting on threats both vague and specific. It's incredibly arousing, of course.
He isn't surprised when she kisses him, hot and angry. He grabs her wrists and presses his forehead against hers, transmitting a detailed image of what he'd like to do to her.
To his surprise, the Doctor pulls away. “Not like that,” she says. To his confused look she explains, “We switch.”
When he understands what she means he laughs. “I don't submit to anyone, Doctor.”
Her gaze and her voice remain steady. “Neither do I.”
Stalemate. They stare at each other and after a moment her expression softens and she lifts her hand to touch his cheek. “It'll help,” she tells him. “It's what you need. There's no need to be scared.”
“I'm not scared!”
“Try something new,” she coaxes. “We've both changed a lot since last time.”
The Master considers his options. He wants the Doctor (nothing new there) but her suggestion that they swap roles is unexpected. A few mental images suggest themselves, though, and he can't pretend he isn't intrigued by them.
Finally he nods. “Fine.”
The Doctor smiles, kisses his cheek. “Good boy.”
He raises his eyebrows at that and she takes his hand, leading him to the bed. She pushes him down onto his back and then produces a pair of handcuffs from her trouser pocket.
He lets her cuff him to the headboard in silence. He tugs at the handcuffs to test the metal. “What's the safeword?” he asks, voice low.
Her smile chills his hearts; “Gallifrey.”
His arms ache by the time she frees him, and the burning pain is welcome.
“Knew you'd like that,” she announces when she gets her breath back. She looks down at him from her vantage point and then lifts herself off him with a content sigh.
He swallows. “If you ever tell anyone I let you do that -”
She rolls her eyes. “You'll what? Kill me? Don't make idle threats,” she says, moving to his side, “makes you look weak when you don't follow through.”
He turns to look at her. “I'd never kill you, you must know that by now.” The words are almost tender.
“Why did you do it?” she asks. There is no need to specify what she means.
“You'd have done it too,” he answers.
“I was afraid you'd say that.” She pushes herself up into a sitting position. “If you'd just tell me -”
She shakes her head. “No point me staying then, is there?”
“I suppose not.” He closes his eyes as she leaves the bed, pretending disinterest and the possibility of sleep. He hears her moving about, the rustle of fabric as she finds her clothes and puts them on.
She doesn't say goodbye. Why would she, when she'll be back here soon enough? The Master listens to the sound of her TARDIS fading into the vortex and starts planning for their next meeting.
All he has to do is wait.