Diedrick is a lean human man of average height, with wiry strength, quick hands, and a narrow, weathered face. His dark brown hair is cut unevenly with a knife, and a pale scar runs from the corner of his left eye to his cheek. He wears patched leather armor beneath a soot-stained gray coat, soft boots, and a collection of hidden pockets. His eyes are sharp hazel, constantly measuring exits, valuables, and possible threats.

Diedrick is observant, irreverent, and intensely self-reliant. He treats danger like a puzzle and boredom like a personal insult. Beneath his swagger is a guarded loyalty toward anyone who reminds him of the vulnerable children he grew up with. He is quick to laugh, quicker to suspect betrayal, and happiest when he has three escape routes and a secret no one else knows.

Diedrick was left as an infant outside a crowded charity house in the poorest quarter of a sprawling city. The only clue to his family was a small brass token stamped with a broken crown, which he still keeps sewn into the lining of his coat. The charity house fed him for a few years, but the streets raised him. He learned to sleep beneath market stalls, read the moods of guards, and identify which shopkeepers were cruel, which were careless, and which might leave a crust of bread near the back door. By adolescence, Diedrick had joined a loose family of street children who survived through pickpocketing, message running, and rooftop burglary. An aging locksmith named Mara taught him the difference between a lock that should be opened and one that should be left alone, while a retired cutpurse taught him how to disappear in a crowd. Diedrick eventually stole from the wrong noble household and discovered that the broken-crown token matched a seal hidden in their private records. Rather than wait for the noble family to decide what to do with him, he fled the city with a rapier, a few stolen tools, and a pet mouse named Nibs. Now he travels as an adventurer, chasing coin, secrets, and the truth about where he came from, though he insists that none of those things matter to him as much as having a door he can lock from the inside.