Tarn is a compact aasimar with warm brown skin, dark hair cut close at the sides, and pale gold eyes that catch light like polished brass. His most noticeable features are his broad, square teeth and strong jaw, which show whenever he grins or chews. His hands are small, steady, and heavily callused across the palms and fingertips from years of lockwork, climbing, and handling rough tools. A faint halo-like shimmer appears around his shoulders when his celestial power stirs, though it vanishes when he is calm.

Tarn is dryly observant, patient around locks, impatient around liars, and more generous than he wants anyone to know. He speaks in short sentences and prefers practical questions to emotional explanations. He enjoys crowded places because crowds provide exits, witnesses, and distractions in equal measure.

Tarn was born in a crowded river district where his celestial blood marked him as strange, but not strange enough to be protected. His mother worked counting cargo for dockside merchants, and his father disappeared before Tarn could remember his voice. As a child, Tarn learned that a bright smile could make people underestimate him, while quiet hands could make their locks surrender. He began as a runner for smugglers, carrying coded ledgers and small packages through markets, then graduated to opening doors that were never meant to open. His criminal career ended when he discovered that one of his employers was selling names of poor families to debt collectors and slavers. Tarn stole the ledger, burned the operation's safehouse, and escaped with only a crowbar, two knives, and a price on his head. He still keeps the ledger's first page, folded inside his coat, because it contains the name of the person who arranged his father's disappearance. Tarn now takes adventuring work for money, information, and the chance to dismantle the networks that once used him. He tells people he is looking for a better life. He is, but he has not decided whether that means redemption or revenge.