An unimaginative member of the Ankh-Morpork City Watch (police force), Detritus is born above the snow line on a distant mountain and never sees a human until he is five. He rises from the status of stupid troll to fairly intelligent troll, thanks to a clockwork cooling helmet that reduces the effect heat on his silicon brain. He is on duty at the Palace gate when protagonist William de Worde arrives to investigate the rumored murder. Otto Chriek gets them past Detritus by taking a picture of him refusing them entrance and William takes down quotes. Detritus orders Fiddyment to take them to Commander Vimes.