In Moving Pictures he was used by C.M.O.T Dibbler hired muscle in his takeover of Century of the Fruitbat Pictures. While in Holy Wood Detritus met and fell in love with another troll called Ruby who insisted that he get a better job than hitting people for money. Detritus' relationship with Ruby has been mentioned infrequently since; in Thud! they are described as 'happily married but childless.' Over the course of that novel, Detritus takes the severely drug-dependent young troll named Brick under his wing, the slight implication being that Detritus and Ruby want children.
As a result of Ruby's insisting he improve himself, he joined the Ankh-Morpork City Watch, and made friends with the dwarf Cuddy in Men at Arms. When Corporal Carrot formed the Ankh-Morpork City Militia, Detritus was promoted to Acting-Constable and it was during this time that he discovered his natural leadership abilities, as he was able to 'recruit' a large number of able bodied men and trolls into the Militia and eventually into the reformed City Watch. When we next see Detritus in Feet of Clay, he is a Sergeant, and by Night Watch he was heading up the Watch's training academy. He accompanied Samuel Vimes to Überwald for the negotiations in Bonk, in The Fifth Elephant, and was temporarily appointed cultural attache by Vimes.
Detritus' name follows the convention of trolls (a geological race) of adopting geological names.
While Detritus does not have much imagination, he is fairly intelligent, by troll standards, especially since the end of Men At Arms, when Cuddy made a clockwork cooling helmet for him, which reduces the effect heat has on the conductivity of Detritus' silicon brain. The helmet stopped working completely in the desert heat of Jingo, but has been repaired by the time of The Truth. Like all trolls, he becomes extremely intelligent as the temperature drops, once almost developing a grand unified theory of everything in several hours when locked in a 'Pork Futures' warehouse.
His lack of imagination results in an interesting interrogation technique; while he cannot think of any questions beyond 'It was you what done it, own up', he never gets bored of asking it. He can, however, be thrown completely by a simple denial. He has started a personal crusade against trading in Slab, which is a narcotic (to trolls only), that 'melts troll brains' (literally).
In contradiction to his species preference, his weapon of choice is not a club, but rather a converted siege-crossbow. Originally this fired a blunt but enormous metal bolt, but after further modifications he made it to shoot a large bundle of wooden bolts at once and renamed the bow as the 'Piecemaker' (a pun on the Colt S.A.A. 'Peacemaker' Revolver or on the nuclear missile "The Peacekeeper MX"), due to the incredible destructive power of the new configuration. Due to the various forces they are under, the bolts, once fired, quickly become an expanding cloud of high-speed burning wooden shrapnel. The first time it was fired, it removed several archery targets, the bunker wall behind them, and a flock of seagulls directly above Detritus. Other notable 'targets' include a bandit who was the first to open the door of Detritus' coach, the gates of von Überwald castle near Bonk, an entire chimney, a weathercock, large parts of roofing, and practically all of Sir Samuel Vimes' shrubbery. It has on occasion been fired at people, but Vimes has generally forbidden this except in special circumstances (such as during the initial attempt to catch Carcer in Night Watch). He prefers to allow Detritus to use it when trying to get into a building, as it is able to open both the front and back doors at the same time. Detritus is very attached to the Piecemaker, so much so that he tried to take it as part of his uniform to a major social occasion. Vimes has taken great care to impress on Detritus that "When Mister Safety Catch Is Not On, Mister Crossbow Is Not Your Friend", however, the lesson still has yet to quite stick, and when the Piecemaker is loaded, everyone in the blast radius with any sense at all tends to be extremely cautious not to make any sudden movements. The sound of Detritus loading his crossbow is described in various Discworld novels with phrases similar to 'the sound of a piano being strangled by a goose'.
Detritus was, when he first joined the City Watch, introduced to people as 'Lance-Constable-Detritus-Don't-Salute!', because at that point, he had not quite gotten the hang of saluting, and when he saluted, he usually knocked his helmet off and himself unconscious. However, this was before he was given his special brain-cooling helmet. Since then, he has not been referred to this way.
During the Novel Men at Arms the Dwarf Cuddy taught Detritus how to count in binary; as Cuddy said, "If you can count to two, you can count to anything!" This may be a reference to computers (Silicon brain, Silicon Processors) but is unconfirmed.