Knee-co is a lean male dragonborn with copper-gold scales, a narrow muzzle, and swept-back horns polished to a dull shine. His clothing is practical and layered, consisting of a dark leather apron over scale mail, numerous pouches, and a tool harness crowded with vials, wire, chalk, and tiny screwdrivers. A battered brass knee brace is strapped over his left leg, not because the limb is injured, but because he uses the brace as a concealed compartment for lock picks and alchemical needles. He stands too close when speaking, tilting his head as though examining people for hidden mechanisms.

Knee-co is bright, restless, and cheerfully untrustworthy in harmless matters. He enjoys solving problems more than being thanked for solving them, and he treats every conversation like a negotiation over hidden components. Beneath his criminal habits is a genuine fascination with invention and a reluctant instinct to help people who are being exploited.

Knee-co learned early that locks were simply puzzles designed by people who lacked imagination. In the back rooms of a dragonborn gambling den, he became useful as a locksmith, counterfeiter, and maker of discreet alchemical distractions. His first real invention was a thumb-sized brass beetle that crawled across a table and stole a key ring without making a sound. The beetle worked perfectly. The escape afterward did not, which is how he acquired his nickname and a lifelong habit of wearing a brass knee brace packed with tools, powders, and secrets. After a job went wrong, Knee-co discovered that his employers had been using his inventions to sabotage medicine shipments and extort small villages. He took the evidence, ruined the operation with a cloud of purple smoke, and vanished before anyone could decide whether to kill him or hire him. Now he travels as an artificer and occasional criminal consultant, selling clever devices to adventurers while quietly looking for the stolen design notes of his former gang. He claims he wants revenge, but what he really wants is to prove that his best invention can be used to dismantle the entire criminal network without anyone noticing until it is too late.