Gendry knows first hand the importance of tempering a blade. What good was a weapon that failed you when it counts? No, you heat that metal till it glows with molten strength that yields to his hammer like clay. Every swing shapes it, each drop of sweat from the intense heat another hiss as he makes the metal sing for him. When it glows bright, shaped just right to defend or protect those who'd wield it, then comes the quenching. The cloud of steam and hissing curse of angry metal as it's dipped into cold to harden it into a weapon. He'd never thought to apply the same process to people but then again no one else is quite like Arya Stark.
He'd seen the heating. Borne witness to the hottest of her furies and watched helplessly as her soul burned to be forged anew. Missed the quenching, that dip into cold that sets the steel into something truly lethal. What had his fierce wold cub found herself drowned in to become this shadow? A living Wraith with steel eyes that cut sharper than any blade he's ever made. Arya stalks the grounds and he sees the fear and awe he'd always known she could inspire. The starved recruit alone had been unforgettable but a woman now grown and sure of herself as she is? Gendry is hard-pressed to keep his grubby hands to himself when those molten eyes glimmer a challenge he is terrified to answer.
Why she'd be interested in a bastard like him has always been a touchy subject between them, be it friendship or whatever is was now. He has always been a little in awe and more than a fair share wary of Arya. Something about her screams feral and dangerous but he's always been drawn to the challenge she represented. Been proud that he'd been counted among those close to her when she'd been lost to the rest of the world. That dangerous scrappy Arry trusted him had been humbling and powerful. A different kind of danger.
Then he'd gone and mucked it up like the bull he is and had lost her. Lost the only thing that ever mattered to him, the only person who'd ever given two shits about a bastard boy with a hammer. His fierce wolf cub. Even as pissed as she'd been she'd still fought for him, tried to protect him from the witch. That memory had haunted his nights for years after. He'd feared her dead after all that happened and had followed her brother part because Davos asked but mostly because this was Arya's favorite brother and how could he not but then...Winterfell.
To be honest he coulda' done with some warning there. She had just appeared from the shadows looking like polished steel. Lethal and gorgeous. His gut dropped and the husk in her voice had created interesting reactions in him that made facing her even harder. She'd grown so strong and fierce and if he'd seen her as a challenge before it's nothing compared to this.
The wolf cub is all grown and her eyes dare him to rise to the challenge she offers. He'd seen that look in her eyes before in what feels like another life and it hadn't really bothered him the way it does now. There is power and want thick in his veins but his mouth fumbles for words. This she-wolf eyed him like she'd like to devour him whole and it sent a lick of fire up his spine as he turns his back to find some semblance of control. It's been years, its madness how she inflames him so easily. There is magic in Arya Stark of a wholly different kind.
Her skill display only fanned the coals of want in Gendry's gut. For weeks he is a smoldering mess for a woman he barely knows (a girl he can't forget) and it is madness he is slowly losing the fight against. Making her weapon is a sick version of foreplay. He can imagine her hands moving over its length, body moving in that silently graceful way of hers as she fought. By the time it's done he's been half-hard for days and beyond shame and into desperation.
Now he is the one heated and shaped anew by this all-encompassing want. The desire she inspires will forge him into something he cannot yet name but can no longer bear to deny. When he finally has all that sharp ferocity above him, around him, sweat cooling rapidly in the frozen air he feels his soul quench in his love. Forever frozen into hers. It's deadly and he is sure to cut himself on the sharp edges but she is a weapon and he, her smith.