William "Billy" Olmstead was an adviser to Ewekapu Marsh in New Barsmouth. Son of Sera Olmstead and an Outsider, he was for many years a companion to Ewe. He developed unreciprocated feeling for Ewe, which came to a head when Ewe revealed that he was having relations with Johanna Caldwell. In anger, Billy reported this to Ephraim Marsh, Ewe's father. He didn't see Ewe for many years, during which his feelings deteriorated. He was chosen by Ewe to advise him when he was put in charge of New Barsmouth, at the time a new construction. He accompanied Ewe and Xalmor Windrunner to the meeting of the Esoteric Order in Grinwillow in place of Barnabas Waite.
He was drafted into the Esoteric Order and ended up in the service of Ephraim Marsh. Billy was a reluctant servant of the cause and was greatly out of his element. He lacked completely in any sort of offensive abilities or combat knowledge. He was given magical trinkets to make him useful. He ultimate betrayed Ephraim, allowing the Malefactors to defeat him and the Esoteric Order.