Arnaum (given name not recorded) was a resident of Serrofus Major, where he worked as an inn keeper.
Mister Arnaum kept a tavern in the centre of the Serrofus Major capital city. The premises were visited by Maber Castigon in 3745 ELC, and the fugitive rightly assessed that Arnaum's establishment was the sort of dingy, discreet place where he might find assistance in carrying out his plans (→LOTD).
Arnaum recognised that Castigon was a new face, and offered him a drink from an unlabelled bottle, stating that the "first one" was on the house (→LOTD).
Castigon did not care for the beverage, and another man — Collis — called out Arnaum and told him to give Castigon a proper drink. Arnaum was visibly offended when Collis then called his tavern a "shit-hole", but backed down straight away when Collis shot him a look. It might be inferred that Arnaum has had previous dealings with Mister Collis which did not work out so well for him (→LOTD).
No further information is recorded regarding this individual.