This is an exercise in exploring the Arya/ Gendry dynamic & is mostly just pure smut! Enjoy! I may write more chapters if people want, let me know in the comments!
(NB: A bit of artistic licence so, Arya is around the same age as Gendry, set during their time at Harrenhal based on the tv show, no real spoilers)
Gendry tosses over trying to fall asleep, staring out into the darkness. The camp is quiet except for the soldiers on watch. He hasn't slept properly since they were on the way to the Wall. Now in Harrenhal with the stench of blood and shit in his nostrils and the fear of the place he can't sleep. That isn't the real reason. Gendy huddles smaller into a ball and sees her face. He can't stop seeing her face. He remembers seeing her the first time, watching those boys rough her up, he thought she was a boy then. A slight young boy of around 16, not much younger than himself. It didn't take long for him to figure out that she was a girl. Arya. She didn't seem high born though. When he thought she was 'Arry the boy, he seemed tough, and steely with honour. Ever since he had confronted her that she was a girl, he couldn't stifle the growing feeling inside him. He tried to convince himself it was a brotherly protective feeling, but he knew it wasn't.
When they had been taken to Harrenhal there wasn't time for anything except fear. Gendry felt more fear for Arya than himself, although the fear of being discovered as the one the soldiers were looking for was very real. All that though, wasn't why he couldn't sleep. It was her face, that short roughly cropped hair framing her face. Those soft open eyes that she tried to hide behind with the steel in her stance and the steel of her 'needle'. The swagger in her step, just like a man's. Those muscly arms draped in the rough cotton of the oversized man's shirt and pants. The way they draped across her thin frame, making your eyes imagine what was underneath. No! He thought. He tried to block out the thoughts of her, he would have to be at work in the smith in a couple of hours and he needed to rest.
As Gendry stared up at the sky as it turned pale, turning from black silk to blue velvet, he sighed. Closing his drooping eyes, he finally fell asleep with the thought of Arya's lips on his.
The next day Gendry worked in the smith sweating despite the cold air. Gendry took off his shirt to cool the sweat on his skin. He dipped a sword in the water barrel and checked it for trueness and keenness. Out of the corner of his eye he spied the object of his thoughts. Her dark hair tussled, the oversized shirt dwarfing her small frame and those trews the gave her that masculine look. Gendry's grip on the sword slackened at his side as he couldn't help watching her as she strode across the filthy courtyard. She wasn't the slight girl that he mistook for a boy any more. Beneath the baggy trews and shirt, she had filled out. Her hips curved more and her chest more prominent.
"What?" Arya demanded, now standing in front of a gormless Gendry, his jaw slack. He tried to think of a quick reply, but his mind was blank. "Gendry, you'd be dead a hundred times over if it wasn't for me" Arya grinned. Finally Gendry came to his senses. He still said nothing, but turned to put the new forged sword in a pile. As he turned he thought he saw Arya biting her lip, her eyes confused. Or maybe he was just imagining things.
Later that night, dog tired after no sleep the night before Gendry threw himself on his thin bedroll in a corner. His eyes closed even before his head hit the ground.
It was pitch black and Gendry didn't know what had woken him. He lay still straining his ears. He heard a scuff of a boot on a rock. Before he could turn around to see what had made the noise he felt a cold blade pressing against his throat. He could feel his pulse hot against the cold dagger. He felt someone lean down behind him, felt the blade jamming into his neck, but not drawing blood. His breath caught in his chest, even if it wasn't he dare not cry out, he'd only get punished anyway.
Gendry lay still, half with fear, half with resolution. When moments passed and still nothing happened, Gendry began to wonder and plan an escape, but that cold steel was still hard against his throat. His throat would be cut before he could get around at him. He could feel them breathing they was so close. Lying there in the darkness behind him. Gasping a breath Gendry whispered "If you're going to do it, get it over with". He felt the dagger slacken and his breathing eased, his chest heaving in and out. Suddenly the blade was gone. For a second he didn't move and then he spun around reaching for his sword leaning against the stone wall.
In the darkness Gendry scoped out the shadow of the man standing in front of him. Out of the shadows a voice came "You sure you know how to use that blade, Gendry?". His heart stopped a moment. Then Gendry's heart started pounding as the figure came towards him. In the pale light of the moon, he saw their face a handsbreadth away. "Are you afraid of me Gendry?" Arya said quietly. Gendry tried to gather his thoughts, make sense of them. "I could kill you with one slice of this dagger" she whispered pressing it up against Gendry's chest, nicking a whole in the cloth of his shirt.
"Why?" Gendry breathed. "Don't you know?" breathed Arya. Gendry carefully lay down his sword quietly. "There Arya, I'm at your mercy, you know that you're a better swordsman than I'll ever be" he said flatly staring into her blue eyes. "Is that how you think of me Gendry?" Arya said in a hurt voice. Gendry didn't say anything. Arya stepped back letting her dagger drop to her side, her face turned to the ground. Gendry felt confused, he didn't understand, why was Arya coming upon him in the dark of night at bladepoint to interrogate him, did she think he would betray her? While all these thoughts were broiling in Gendry's head, Arya whispered defiantly "I aint no lady". Gendry's head shot up, suddenly it was clear. He reached out his hand to her face drawing it up so he looked straight into her eyes.
He stared right into her face, his lips so close he could almost taste her and said with all the passion in his heart "I don't want a lady, I want you". Arya's eyes widened, but before she could protest Gendry kissed her hard on the mouth. He felt her knees buckle beneath him. He grabbed her waist pulling her closer to him. Breaking apart both gasping for air their bodies still touching, Gendry drew breath enough to say "I've always loved the way you look in those boyish trews, how you could spar with any of the best soldiers, I don't want some Lady in a tower.". Arya looked into his eyes, scrutinising him before saying "I never thought I would want a man. I never wanted to be married off to some Lord, like Sansa and the other Ladies."
Using her speed and stealth Arya pressed Gendry hard back up against the stone wall of the courtyard. "I can't stop wanting you" Arya breathed pressing her self against Gendry's hard muscular body, kissing him hard, he moaned into her mouth. Gendry felt himself getting aroused, Arya straddled one of his thighs pressing her knee hard against his centre, feeling his manhood pressing against her.
Arya took one hand out from beneath Gendry's tight grip around her waist and stroked the waist band of his trews. She felt his muscles tighten beneath her. Arya felt herself getting wetter as she pressed herself harder against Gendry's thigh. She felt his hands fondling her hips as he stroked her, touching the soft flesh of her stomach, reaching up beneath her linen shirt to her breasts. Arya gasped as Gendry fondled her breasts, her nipples hard and begging to be pressed, her chest thrusting out closer to him. He circled his calloused blacksmith thumb around her nipples and pinched them.
Their breath came out in steamy gasps in the darkness. Gendry dropped his hands back down to her waist, Arya feeling a little disappointed until he pulled her around to stand pressed between his legs. She could feel his heat pressing into her and she surrendered herself to him completely, letting him lead her. Gendry pushed one hand down her pants and stroked her wetness making her moan softly in the stillness. Slick with sweat and aroused, Gendry pushed away from the stone wall and turned to push Arya so her back was against the wall instead.
He looked into her eyes, their immense blue depths steady and sure, he asked for permission with his eyes. Arya responded with her whole body wrapping her legs around his waist, he held her up against the wall, his arms at her waist, and pushed himself inside her. She gasped. Gendry stopped for a second, looking at her, unsure. He looked up at her, her brown hair tussled and sweaty around her face. He felt her push against him, and he could no longer hold himself still as she leant forward and whispered in his ear "Fuck me".