 As he has been residing in Camp Jupiter for no more than a year, Frank is initially considered a "probatio", or rookie, of the Fifth Cohort.Before the quest to free Thanatos, however, his cohort's centurion, Gwen, decides to retire and give her position to Frank.Later, in "The House of Hades", Jason surrenders his praetorship to Frank, who uses its authority and Diocletian's Sceptre to lead an army of Roman skeleton soldiers against the monsters in the Necromanteion.