Their… liasons, for lack of a better word, followed a strict set of rules.
Rule one: they never spoke of it. Not before, not during, not after. Years of combat together had attuned their senses to non-verbal cues. In the beginning, it started with just a look. Their eyes met across the table where blueprints were laid out. He raised his eyebrow. She licked her lips. By the time he rounded the table, she had her boots off and her pants on the way. By now they could read each other's bodies so well, all it took was the roll of his shoulder, the tilt of her head.
Rule two: never in a bed. The table in his quarters. The desk in hers. A couch, a chair, against the wall. Once in the elevator. She particularly enjoyed the floor in the observation deck, right by the window. On her knees, she watched the stars sparkle through their reflection as he dug his fingers into her bare hips and thrust into her with tantalizing slowness.
Rule three: no one gets left behind. It didn't happen often, but the first time he came before she did, he almost seemed offended when she assumed they were finished. She reached for her pants and he grabbed her wrist, giving her a look that said "The fuck are you doing?" Then he got on his knees to finish what he started.
Rule four: last to the finish line makes the drinks. And there were always drinks, be it scotch or wine or morning coffee. Even if they had to go to a common area of the ship, the ritual was always the same; they'd sit or stand side-by-side, talking about an upcoming mission, or a previous one, or swapping war stories. Miraculously, crewmembers rarely interrupted these moments.
They never took off more clothing than necessary; this was less a rule and more a matter of circumstance. And "necessary" was a subjective term - he often found an excuse to leave a bite mark on one of her shoulders; he had a thick scar high on his ribs that she liked to skim with the pad of thumb.
Shepard couldn't sleep. Fuck it. She jabbed the comm button and paged him up to her quarters. The hand she ran through her hair was shaking; these days it seemed like the only thing that steadied her hands was holding a gun.
He knocked once and let himself in. Before she could comment on the bottle he brought, he backed her up against her desk, tangling one callused hand in her hair as he plundered her mouth. He let her tear his shirt off before he dragged his teeth down her neck and hauled her tank top over her head. She wrapped her legs around his waist as he lifted her up against him. She could feel the cold press of the bottle against her ass through her sweatpants, and she stifled a laugh as he stumbled through her cabin.
He dropped her back to her feet and she tottered back half a step, bumping into the bed. Her breath caught in her throat. His eyes boring into hers, he stripped the rest of his clothes off slowly, as if waiting for some signal from her. She wriggled out of her pants, trying to take in every inch of his naked body, The second she stepped out of her pants he grabbed her again, kissing her so hard she thought her lip would split, and they tumbled onto the bed. He explored her body with his hands and mouth, making her nerve endings sing, but it wasn't what she needed.
"Zaeed," she panted, digging her nails into his shoulder.
"Don't tell me you're gonna beg," he growled, his stubbled chin grazing her breast
She smiled wryly. "I never beg," she whispered, rolling him over and climbing on top of him.
He dug his fingertips into her thighs as she sank onto his cock. She rode him hard, her palms pressed against his chest, and she was still reeling from her own orgasm when he came. She collapsed onto the bed, trembling.
After a minute he sat up. She watched him, drinking in the smooth, finely-muscled planes of his back, the expanse of skin marked by fewer scars than the rest of him. But instead of his clothes he picked up the bottle, offered it to her, and stretched back out on the bed. She took a drink and passed it back; he took a drink and set it next to the clock.
"I tell ya, Shepard," he said, tucking his hands under his head, "I could get used to this."