I wanted to do a steampunk type story, with airships and that sort of thing.
The Mechanics of the Underground, who live far beneath the Capital, are a secret society, they mostly cater to thugs and gangs, and the leaders of such groups. The Mechanics specialize in mechanical limbs and on every boys tenth birthday, they take that boy's right arm, and make him make a new one alone. Its an initiation and every boy must do it. Girls are sent Above, to be raised there, for there are no females among the Mechanics.
The boy who was to be initiated today had been sold to the mechanics by a family desperate for money. Their older son had lost his leg in the war and they owed the mechanics, so they took the small boy as payment. Now that boy was laid out on the block, his right arm splayed out so the axman could have a clear shot. The boy lay without protest, he'd seen this done countless times and knew that he had to go through this. It was the way of things. The sharp blade came down, and there was blinding pain. The boy blacked out almost immediately.
When he came to, his entire shoulder was covered in bandages, and he was in one of the many workshops in the underground city. The shelves were covered with new tools, and a small furnace sat in the corner. Blueprints and plans were rolled up like scrolls on special shelves across from the tools. The plan he needed was already out on the workbench, unrolling it awkwardly the boy spread it out and tucked the corners into the special grooves in the workbench intended for the purpose. Grabbing the tools needed, he set to work, shaping each mechanical finger and etching the fine whorls and spirals of a fingerprint. into each one, before fitting it to the main part of the hand, etched in the appropriate symbols then attached it to the arm, a smooth, two peiced bit of machinery with the shoulder joint on the end meant to fit exactly over the wound. A shoulder pad had replaced the bandages already and so all that was left to do was plug the arm in, and it would connect with the nerves and function just as a real arm would.
The boy did so, and after a spark of pain, he could feel his arm again, he flexed the fingers experimentally to find that they worked beautifully. Dipping his new hand in a pot of red paint, he put his handprint on the wall, marking this new workshop as his. The boys name was Jecoda.