Disclaimer:I don't own IPS or the characters!

Warning: This is rated M for a reason, and that reason is rough, borderline-violent sex. NOT non-consentual/rape, but it gets a bit closer to the line than usual. If that will bother you, don't read this fic!

Author's Note: Inspired by BuJyo's A Single Strand Unraveled, which is excellent. I think everyone here has probably read it by now, but if you haven't, you really should! Um, after you read this! Anyway, the two of us agreed I should write some hot angry sex, so... here it is! Thanks for the inspiration, BuJyo! =D

Spoilers: S3 finale.

Taunt

"Did you think," Marshall's voice murmured from a dark corner as Mary turned on the light, "that you could just run off to Mexico, and I wouldn't care?"

Mary nearly jumped out of her skin. She hadn't expected anyone to be waiting for her when she arrived home, had, in fact, caught a cab just so she wouldn't have to have this awkward conversation with Marshall. She knew she'd hurt him, oh yes, she wasn't so oblivious that she wouldn't be aware of that fact, but he had backed her into a corner. Mary Shannon only knew one way to get out of corners, and that was to come out spitting hellfire with guns blazing, bringing with her the certainty that whatever had put her there would be laid to waste.

"Jesus mother-humping… what the fuck are you doing here, Marshall?"

He got up slowly, made his way toward her with an expression on his face that Mary had never seen before; she'd seen him angry, but not like this. He was livid, and it burned throughout him with an almost frightening intensity.

Relax, Shannon, she told herself. This is Marshall we're talking about, the man who fights his battles with words. Nothing's going to happen. Still, there was no sense in provoking him, and she forced a calm demeanor as she set down her suitcase and locked the door.

"Did you really think," he growled this time, a menacing rumble that froze her on the spot like prey, "that you could go to Mexico…" he had her backed against the door now… "with Faber…" he nearly spat the word… "and I wouldn't give a damn?"

"It's none of your goddamn business what I do," she snapped back, cornered once more and not pleased about it, and already ditching her plan of non-provocation. It was a crappy plan anyway, so fuck it. Fuck him, too.

His hands gripped her shoulders and pinned her to the door, hard. His lips were on hers, sudden and urgent, and she felt a charge race through her body as she reacted. Yes, this was something she understood, the heady blend of sex and anger that could only be delivered by someone well and truly pissed off, and God help her, she wanted it.

"It's none of my fucking business?" His hands moved to grip her denim-clad thighs, hiking them around his waist as he lifted her off the floor and pressed himself against her, his words ragged in her ear. "No concern of mine that you let him inside you, that you let him fuck you?"

Goddamn, Mary thought as she found herself suddenly breathless. He was rock-hard, almost painful as he ground against her, and she was enjoying every second and every throbbing inch, craving the punishment she'd so richly earned. You're a sick bitch, Shannon, you know that?

"He wasn't even that good," she whispered, and Marshall lost whatever fine thread of control he had still possessed up until that point; he clamped his teeth on the skin of her neck with a strangled, inarticulate cry, and Mary was certain it would leave a mark even if it didn't draw blood.

"Goddamn it, Marshall, give it to me already," she ground out hoarsely.

In an instant, he had her bent over the back of the couch, his chest pressed to her back and his breath hot and hard against her neck as he fumbled with the button on her jeans. In another heartbeat her pants were around her knees and she could make out the sound of his belt being unbuckled and his zipper dragging down. One of his hands gripped her hip as he used the other to guide himself to her entrance - oh God, was she ready for him - and both of them groaned as he surged into her from behind.

He filled her, almost painfully as he was so hard, and dear God, he was big; at least, bigger than she'd have guessed from feeling him restrained behind cloth, and Mary found herself near the edge already as he thrust into her urgently. His hands slid under her shirt and pushed it over her head, taking her bra with it roughly, and she cried out at that discomfort, but only for a moment as the undeniable pleasure of his movement within her overtook her once more. He plunged into her again and paused, and for just a second she thought he might be done, but instead he yanked his own shirt over his head with an irritated growl and sent it flying, obviously desiring more contact as he pressed his bare chest to her back. He set a strong pace once more, forcing her to brace herself against the couch-back with her hands; the piece of furniture began to inch across the floor in response to their frenzied intercourse.

Mary was crying out wantonly now, a torrent of guttural moans and obscenities laced with his name and Marshall fuck me oh dear God yes she was over the edge, spasming around him as he buried his face in her neck with his own hoarse cry and pulsed his release in her depths. After that moment of ecstasy in which he had gone rigid against her and gripped her tightly, Mary felt both of them go completely boneless and they collapsed on the floor in a heap.

She stared at the ceiling for a moment, trying to make herself believe that had just really happened, that she and Marshall had just had amazing, mind-blowing sex against the back of her couch. She cast a glance at her partner. As the haze cleared, a look of horror crept over his features as he looked at her. He reached a shaky hand toward her; trembling fingertips traced lightly and fearfully over reddened handprints on her hips, tiny raw patches of skin where her bra had been torn free, the bite-mark on her neck, and Mary saw tears welling in his eyes.

"Oh God," he whispered shakily. "Oh God, what did I do?"

He pushed away, scooting back blindly until he was sitting against the wall. He buried his hands in his hair as he looked down, tears of shame and guilt spilling over and landing on the floor.

"Oh, Marshall, no," Mary babbled quickly, trying to scramble after him and slipping, caught in the pants that still hung around her knees. She kicked her way out of them - faster than pulling them up - and righted herself, finishing the crawl to his side. He shrank away from her and she was after him, pulling him into her arms as he broke into sobs.

"I'm so sorry, Mare," he choked out. "I'm so, so sorry."

"God, no, Marshall," she murmured frantically. "I liked it. God help me, I liked it. If I wanted to stop it I would have, so don't cry."

"What?" he asked in confusion, looking up at her with terrified blue eyes.

"I'm the one who should be sorry," she continued. "That speech you gave in the office… I wanted you and I was too scared to say so. When I went to Mexico, I don't know if I was trying to run away or force you into a corner like I thought you'd done to me. Then, with this… I didn't stop you. I wanted this and I liked it and none of it was your fault."

"Mary," he whispered, his eyes tearing up all over again, "how can you excuse what I just did?"

She looked at him for a moment, trying to think of the right thing to say, the words that would fix this, but words were his tools, not hers. Instead, she leaned in and kissed him, a light kiss on his lips but she let it linger, let him come to her, and after a moment's hesitation she felt him give himself permission as he shifted into her and kissed her in return. His hands reached for her tentatively and she let herself slide into his arms, rewarding his acceptance with the one thing she knew he truly wanted: herself.

"Mare," he breathed in her ear, "do you mind if I stay tonight?"

She couldn't help but smile at the hope in his voice.

"I would mind if you didn't, Numbnuts."

A/N: Well, there it is. Hit review, and let me know what you think! =)