Oster was a knight of Edgemont's champion the Dreadknight. After the Dreadknights death Oster joined The Rogue Knight's knights and is now assumably a member of the unseen. He was the 3rd in command when a knight of the Dreadknight and one of only 3 of 12 knights who stayed loyal to The Rouge Knight along with Raul and Desmond.

Oster and Desmond also traveled with Honor to find Destiny. They did so succesfull but Oster met his demise when he and Leo we're killed by Nandavi at Gamat Rue when trying to find Ragio.