"It's pretty complicated, but there's a housing surgically implanted into what's left of my leg at the base of it, that ties into my nerves to power it and sort transmits the nerve impulses to the rest of the automail so the right things move for what I need it to do," Hiccup explained. "It's all mechanical, though, gears and other complicated moving parts. Pretty intricate. I have to do a lot to maintain it."