Finnegan is a compact lightfoot halfling with warm brown skin, thick russet curls, bright hazel eyes, and a broad, expressive mouth that shows a gap between his front teeth whenever he laughs. He smells faintly of hot brass, cinnamon, lamp oil, and whatever spice he last used to clean a stubborn gear. His scale mail is carefully fitted over a soot-darkened leather apron, and his belt carries tiny tools, labeled vials, and several harmless-looking mechanical curiosities.

Finn is bright, sociable, and relentlessly curious. He treats every problem as a design challenge and every stranger as a possible source of an interesting story. He is generous with repairs, suspicious of grand promises, and delighted by small luxuries such as hot tea, polished brass, and a perfectly balanced screwdriver.

Finnegan Copperkettle was born above his family's brassworks in the halfling quarter of a busy trade city, where every room hummed with bellows, clockwork, or an argument about whose kettle had the better whistle. He learned early that a well-made object could solve more than a practical problem. It could comfort a homesick traveler, keep a poor family warm, or make a tyrant's locked door considerably less certain. His first inventions were small, clever things: self-stirring soup spoons, spring-loaded boot brushes, and a tea kettle that sang three different tunes depending on the temperature. As he grew older, Finn joined the city's Tinkers and Metalworkers Guild, earning a reputation for repairing tools that other craftsmen had discarded. His guild master encouraged his curiosity, especially after Finn discovered that his careful experiments had begun producing unmistakably magical effects. When a wealthy patron tried to claim one of Finn's inventions as their own, Finn responded by releasing a swarm of clockwork beetles into the patron's counting room. The beetles did no harm, but they rearranged every coin into neat little messages reading, "Pay the maker." Finn left the city soon afterward, carrying his tools, his unfinished designs, and a firm conviction that useful magic belongs in the hands of ordinary people.