As a Traveler that had been born with an adult mind, Julian had enjoyed the singular privilege of watching his own older sibling grow up.
In the flesh, Augustus had been taller and less pudgy than him, losing his milk teeth while Julian had physically toddled after his brother in the sprawling halls of the central palace. But mentally, there was something in Augustus that reminded Julian greatly of his own son in his first life, back when his son was young and optimistic. At least, before his son had been hurt by Julian's distant parenting.
While the emperor was happy to leave Julian's rearing to the empress, he had bestowed upon Augustus enough fatherly affection that Augustus was a well-adjusted lad who was happy to impart the same treatment to his younger brother.
Naive and idealistic, Julian had mentally critiqued Augustus during their early lessons, but kind.