House Ladrian is one of the noble houses of Elendel, the capital city of the Elendel Basin on Scadrial. Once a prominent and wealthy family, the house fell into severe financial difficulty before Waxillium Ladrian reluctantly returned from the Roughs to assume leadership. Under Wax's stewardship, House Ladrian has stabilised - though his unconventional background as a frontier lawman and his habit of getting into gunfights make him a poor fit for the polite world of Elendel high society. The house's fortunes are further complicated by the actions of Wax's uncle Edwarn, who was secretly a senior figure in the Set.

The Set is a secretive and powerful organisation operating across Scadrial, combining elements of a criminal syndicate, a religious cult, and a conspiracy with cosmic-scale ambitions. Led by figures including Edwarn Ladrian - uncle to Waxillium Ladrian - and later by Telsin Ladrian, the Set seeks to harness Hemalurgy, advanced technology, and alliances with forces beyond Scadrial to reshape the world according to their vision. Their activities include kidnapping people with Allomantic bloodlines, stockpiling weapons, and infiltrating the Elendel Senate. By the events of The Lost Metal, the Set's true purpose is revealed to be serving the agenda of the Shard Autonomy, an outside god whose influence threatens all of Scadrial.