I just thought the setting sounded sexy. It isn't necessarily related to when Sherlock saved Irene from having her head cut off. Hope it's ok.

...

Deep in the Arabian desert, the setting sun shone a beautiful orange glow through the barred window of the large cellar that Irene and Sherlock were trapped in, awaiting either their death or eventual rescue. They're clothes were torn, they were hungry, tired, battered and bruised. Irene wore a black silk pencil skirt, just above the knee, a ripped off-white shirt and bare feet.

Irene stood in front of Sherlock, who was sitting on the filthy concrete floor looking up at her. He had managed to keep all of his clothes on, his white shirt, black trousers, shoes and black blazer.

"Do you love me Sherlock?" Irene asked

Sherlock continued to stare at the woman, eyes fixed on hers. He opened his mouth fell open slightly as Irene moved towards him. He shifted involuntarily as she moved closer, and closer, until she was standing directly above him.

"How's my pulse now sweetheart?"

She offered her wrist for him to feel, baring a cheeky grin, but he chose not to, instead he continued to flicker his eyes over her face, her body, her mouth...

Irene crouched down in front of the pale man, reaching for his dark curls to tuck them behind his ear. She knew she could break him, make him crumble before her, she knew exactly what she was doing, she would get what she wanted, no doubt about it. She knew he wanted it too.

"Do I make Sherlock Holmes nervous?"

"Why would you?" Sherlock snapped

Irene leaned back and smirked. "Oh so you will answer that question, come off it, look at you..."

Sherlock closed his mouth, looking her up and down.

Irene exhaled slowly, the sound of her breath escaping her lungs... Sherlock had to fight to keep his eyes from cluttering closed. All he wanted to do was grasp her small waist, to feel her body close to his, her warm breath...

Before he could finish his trail of thought, she straddled his lap, comfortably squeezing the man between her thighs. She bit her bottom lip, smirking, her eyes flickering from his chest to his throat, to his mouth... and back to his eyes where she could observe his pupils. He was obviously managing to keep his self-control, pupils were still small, tight, hard to budge.

"Don't..." Sherlock murmured, even though it was the last thing he wanted to say

Irene stroked his soft cock through his trousers, Sherlock had a decision to make, he could keep lying to Irene and himself and keep on hiding behind the straight face, or he could accept that he wanted it, just go with it and let her do whatever she wanted. He remained in this limbo for another few moments until he was awoken by the tug of his button being undone on his trousers.

"Irene..." Sherlock breathed

"What?" She straightened her back, looking down at him. "Do you want me to stop?"

Sherlock didn't respond. He certainly did not want her... to stop.

Irene unbuttoned her off white torn shirt, revealing her black lace bra. She cupped one of her breasts, rubbing her thumb over her nipple.

Sherlock's breathing had become laboured, he was finding harder and harder to keep his cool.

Irene decided she had to try something different. She leaned in carefully, the feel of her hot breath on his lips... Any signs of protest that Sherlock intended of portraying were silenced as Irene slipped her tongue into his mouth delicately exploring every inch, teasing his tongue. She withdrew her own tongue, pulling away, swallowing hard. When she got no reaction, she was about to give up, when she felt those long nimble fingers gently brushing the back of her neck, she groaned under her breath. Sherlock's lips were parted, obviously wanting more. So she leaned in for another go, only to be taken by surprise when Sherlock clumsily pressed his lips into her experienced mouth. The gentle kiss soon turned into a battle of tongues, hot breath, clinking teeth and bitten lips. They broke away from each other, out of breath.

Irene ran her hands over Sherlock's chest, before unbuttoning his shirt, pealing it back so she could admire his chest. She was brought out of her daze when she felt Sherlock's hands on her shoulders, clearly trying to remove the remains of her own shirt. she smiled and shrugged it off onto the floor, along with her bra. Sherlock felt himself transfixed by her breasts. He had of course seen her naked before when they first met, but never had he seen them in this way, this close. This time it was different, it felt right, they were his, for now.

He reached up, rubbing her right nipple with his thumb, just as she had done to herself earlier. A warm rush of blood was sent to her genitalia, causing her to throb with arousal. She gazed down at his now strong erection pressing against his trousers, begging to be released. She had to remember that he hadn't done this before, she had to teach him.

Sherlock watched shakily as Irene began to fumble with his trousers, dragging the zip down, being careful not to hurt him. she delicately brushed his erection with the back of her fingers. Sherlock automatically through his head back against the wall, his hands finally picking up the courage to grip her tiny waist.

Irene pressed her forehead into his, gazing down so she could still see what she was doing. She looked into his eyes, as if seeking permission to continue. She released his very generously sized erection, she admired the amount it had wept for her so far. There would be no foreplay, just sex. She looked deep into Sherlock's eyes, he gazed back hard, beads of sweat forming across his brow. She decided to make her move.

She raised up onto her knees, holding Sherlock's shoulders for support, Sherlock's hands found their way to her back, running up and down her soft skin. She hitched up her black silk pencil skirt so it sat around the top of her legs, there was no need to remove her underwear since she wasn't wearing any, that had been long gone along with her tights a few days ago. Irene slowly began to impale him, it felt so good... it sent shivers down her spine.

Sherlock's pupils bled out faster than he could blink, he gasped as he felt Irene slowly slide down onto his very sensitive flesh, his chest heaved... he took a shaky breath in, trying to keep control, before breathing out hard as he found himself fully engulfed in between her legs. He tried to blink, he couldn't, he couldn't think, he couldn't move, he had never felt anything like it before in his life. He shakily managed to look up at her, he felt his heart pounding against his chest. She bucked her hips slightly, he clung to her, digging his nails into her back.

"Easy tiger" Irene soothed, nipping at his lips playfully.

She began to move, sliding up and down his entire length, feeling him fill every inch of her, to her surprise he pushed his tongue into her mouth, she began to move faster and faster, their bodies writhed against each other, sweaty, hot, flushed... Sherlock grunted deeply with each thrust, he didn't know how much more he could take. His thoughts soon flickered to orgasm. He hadn't had one before. How would he know when... His thoughts were soon cut off by Irene's whines of pleasure. He decided to take matters into his own hands. He raised slightly from the floor and flipped her over on to her back, her legs wrapped snugly around his waist. He regained his balance and made sure he knew what he was doing, before biting her bottom lip as he began to move, he started out slowly, as she had been doing, before beginning to thrust deeper, harder, faster. She clung to his back, digging her nails into his skin, screaming out, the feel of being fucked by Sherlock Holmes... There was nothing else like it.

It wasn't long before he was pounding her hard, Irene crushing his hips with her thighs, Sherlock's bottom lip quivering, his whole body trembling, he was close, he groaned deeply with each thrust, sliding in and out over and over, she was so wet, he could feel her genitalia starting to throb around him.

He could feel a hot wave wash over him, intense heat that burned through his blood, it tingled right through to his finger tips, he began to pick up speed, he took his chance and threw one of her legs over his shoulder to get a better grip. Irene gasped loudly, she couldn't handle anymore, she wrapped her arms around his neck, bringing there foreheads together, she let herself cum, hugging Sherlock's penis tight, she felt the heat wash over her body, hitting her peak of pleasure, crying out his name over an over... she felt complete. Sherlock's thrusts had become irregular and he was grunting into her shoulder. Sherlock was very nervous about th upcoming event of climax, he wasn't sure how to... his face froze, he let out helpless whine as an intense heat began to build, it was overwhelming Irene could feel what was about to happen.

"cum for me baby..." she whispered into Sherlock's ear

And he did just that.

Sherlock's eyes rolled back into his head, face rock solid. He cried out into Irene's shoulder as he began to ejaculate deep into her, his cock pulsating harshly, he couldn't take it, it felt so good, he couldn't move, he managed to choked out a helpless groan, his body shuddering... he pressed his body into hers, he needed to feel as close as possible to her right now.

After what felt like a lifetime, he felt himself cool back down, still shaking, gasping for air. He kissed Irene's forehead, managing a weak grin.

"I love you... Irene" he murmured

Irene smiled, catching her breath. Sherlock still inside of her, completely and utterly spent. She knew this was the man she wanted to be with for the rest of her life. No doubt about it.