This was originally a kink meme response that I abandoned as having not quite the right tone. The prompt was "Buffy whipping Giles", but the kink here is indirect.
The manacles were Council-issue, as was the leather whip. The manacles were magically enhanced so they were equal to the strength of a Slayer in need of chastisement. And the whip was also specially designed, hand-made by Council craftsmen to an ages-old pattern, the lashes tipped with silver beads. A set was issued to every Watcher when he took his oath, when he used his blood to sign the contract that binds him to his Slayer until her duty is ended.
Buffy had discovered them in a box with the Cruciamentum drugs, hidden in the back of his closet behind the chest of winter clothing he'd never wear in Sunnydale. He ought to have destroyed the lot, but he'd filed it away just in case. And so his Slayer had found them. The manacles, the whip, the drugs, the manual that instructed Watchers how to use them on their charges.
Giles sat on the edge of his bed and polished his glasses and watched Buffy skim through the manual. Once upon a time she'd have thrown it at his head and exploded at him, vanished from his life for a couple of weeks of sulking. Not any more. Buffy had learned restraint. The value of thinking before acting.
"They're sick fucks," she said, at last.
"I shan't quarrel with that description."
"Did you ever consider using this stuff on me?"
"There were moments when I was tempted, but in truth, no. Even before I met you, I knew I wasn't capable of it."
"Why did you keep them?"
Giles spread his hands. "In case we needed them for another purpose."
Buffy approved his caution. Clever Buffy. Practical Buffy. Tactical Buffy. She had ideas. The drugs might be handy some day if Faith ever escaped from prison. The manacles as well. And as for the whip--
"It'll be kinky," she said and she gave him that bright smile that he rather worshipped. Unfortunately for him.
His Slayer practiced another sort of restraint with him, the more literal sort. The sort that had him on his knees raising his wrists to her so that she might fasten the Council's manacles around them. The sort that had his body awake and aroused and eager at the sound of the locks clicking shut. He would have all the time in the world to think later, while his lovely, devious, deviant Slayer chastised him, wrung blood from him, and received his most fervent oaths of devotion.