Mark her.

You unbuckle your belt, the sound sharp in the quiet room. She doesn’t turn her head, but you see the way her shoulders tense, the way her breath reacts to the rustle of fabric and the zip of your fly. Your cock has been hard for hours, aching with the need to mark her and claim her in the most primal way possible. You step closer, the heat of her body radiating against you as you stroke yourself slowly and deliberately, your eyes admiring the curve of her back and the dip of her waist as she offers up her battered ass to you.

You speed up your strokes, imagining all the things you're going to do to her once you're done. In a few seconds, you're there, all the day's pent-up arousal coiling tightly in your stomach before exploding all over her. Your cock twitches as thick ropes of cum splatter across her lower back and down her ass, staining her button-up shirt. She flinches as your load hits her over and over, the heat of it steaming in the cold air of the office. You stroke yourself through the last of your orgasm, milking every last drop onto her before wiping the tip on her blackened ass-cheek, watching your cum drip down the back of her thighs and knees.

"Go home," you say, tucking yourself back in.

She stays bent over for a few more seconds, as if she's unable to move, her body trembling, her ass glistening with your cum, until she finally straightens herself and pulls down her skirt. You watch as the fabric darkens as your load seeps through, her entire back a painted mess. She composes herself, wiping the sweat from her brow, before reluctantly leaving the office without a word.