Early in 98 he was promoted to the position of praefect of the public treasury in the temple of Saturn.
Rivalry had already existed between Stilicho and Rufinus, the praetorian praefect of the East, who had exercised considerable influence over the emperor and who now was invested with the guardianship of Arcadius.
Having entered the Roman army, he rose to be praetorian praefect in the Persian campaign of Gordian III., and, inspiring the soldiers to slay the young emperor, was raised by them to the purple (244).
He moved that the title of pater patriae should be bestowed upon Augustus, and yet resigned the appointment of praefect of the city after six days' tenure of office, because it was opposed to his ideas of constitutionalism.
Plots against his life naturally began to spring up. That of his favourite Perennis, praefect of the praetorian guard, was discovered in time.