Explanation: The Roman Emperor Vespasian had two sons - Titus, and Domitian. Titus was 12 years older than Domitian - which means that when Domitian was still at home with his mother, Titus was off as a legal adult, accompanying Vespasian to the provinces, literally saving his father's life in battle, and generally showing himself to be a party boy, bicon, and accomplished military commander. Naturally, after spending almost a decade abroad soldiering with Titus, and very little time at home with little Domitian, Vespasian became much closer to one than the other. Domitian ended up growing into a spite-filled, irritable, brooding creature who got along with no one and had a constant need for validation.
Vespasian became Emperor, and Titus became Emperor after Vespasian's death, becoming a universally praised and beloved Emperor. Due probably in no small part to his daddy issues, Domitian went on to be a terrible Emperor after possibly assassinating Titus and assuming control of the Empire.