Peculiar Prompt: Broomstick servicing kit, stuck half in/half out of a window, caught in the act.
"No, see," Ron said around his cigarette butt. He tossed it to the ground, flipped his broom bristles-up and smashed the glowing butt against the grass. "That's the beauty of it. The service window is like," he held a hand level against his waist, "this high. You don't have to talk to him at all."
"Huh," Harry huffed. "And he does weatherproofing?" He scraped flaking varnish from his broom handle.
Ron pointed the end of his broom at Harry and wiped the cigarette ash, chlorophyll and dirt away. The wood gleamed like brand new. "And fireproofing."
It felt a little like standing at a urinal. His broom tapped his inner thighs while Malfoy rubbed it. A distracting urinal. He tried to ignore the vibration of the polishing spell against his balls.
The window was tiny. Just a little opening with a swing-down stained glass pane of a golden broom in a cerulean sky. Harry rested his forearm against the sign on the brick wall:
Basement Casement Abasement
Insert knob end to rider depth.
Insert broom bristles to rider depth.
Harry held his broom tight, his fist grinding against his dick as Malfoy worked his shaft in long, languid strokes.
"Harry!" Hermione's voice was an ice bath. "What are you doing in this part of Horizont?"
"I-" Harry's broom thrust lazily between his legs. "Uh-"
Hermione's eyes were a dot matrix printer scanning his whole body, flushed face to white knuckles and back again.
Harry gulped. "Malfoy's polishing my knob."
"He's what?!" she squawked.
"You know. Polishing my wood."
"He's about done rubbing it out. I think."
Hermione's face was air dry clay. She blinked back to life and licked her lips. "You think?" She stepped up behind him, hands on her hips. "You think you're about done?"
"Yeah, I-" Two taps hummed against his crotch.
"Hang on, he wants me to turn around." Harry waited for Hermione to step back and give him room. She didn't. "Back up, 'Mione."
"I need space to pull it out and swing it around."
"You..." Hermione gulped. Her eyes were all Arithmancy. "...to swing it around..." She picked at her wedding ring, gazing into the middle distance.
"Back up. I have to turn around so he can finish up."
Hermione went pink, then red, then white, then down. Harry shuffle-stepped over her as she swiftly came to. He turned around and carefully inserted the bristles of his broom through the window.
Hermione looked up, blinking unfocused eyes at the gleaming shaft hovering over her. "My God," she whispered reverently. "I married the wrong one."