Explanation: Succession was often a major concern in the Roman Empire, where the position of Emperor was only semi-formal and consisted of numerous titles, which were not directly inherited by familial fiat. The mad Emperor Caligula, who constantly needled members of his personal guard, the Praetorians, must have been relieved (/s) when they came to tell him that they made a succession choice for him!
His uncle. An older man. Who would be succeeding Caligula promptly, as soon as Caligula was done bleeding out on the floor.