"Hoc age! Accipe ratum! Repete!" went the cry. “Take that! So be it! And again!” According to Suetonius these were the frenzied shouts of the plotters that surged toward Caligula as he left the Palatine Games after noon on January 24, A.D. 41. These were men who had all once sworn loyalty to their victim, but growing anger had boiled over into a determination to end a hated emperor’s life.
It was not always so. Gaius Julius Caesar Germanicus, better known by his childhood nickname of Caligula—meaning “little boot”—had once been popular, but between A.D. 39 and 40 his character changed. There were rumors that the emperor was unwell and some spoke of a disease; others described a personality-altering potion he had been given by his wife, Caesonia. Whatever the cause, Caligula grew nasty and it was the Roman upper classes that suffered most. (Caligula wasn't the last emperor to be assassinated: Elagabalus's hard-partying reign was also too much for the Roman Empire.)
According to his biographer Suetonius, Caligula believed himself to be a god and often said: “Remember that I have the right to do anything to anybody.” He humiliated senators by making them run behind his litter or forcing them to fight for his amusement. Suetonius wrote, "When the consuls forgot to make proclamation of his birthday, he deposed them, and left the state for three days without its highest magistrates."