Julio-Claudian dynasty reign as being strongly influenced by his mother Agrippina, his tutor Seneca, and the Praetorian Prefect Burrus, especially in the first year. He was made Emperor over his step-brother, Claudius' son Britannicus, who he had killed. Agrippina was believed to have poisoned Claudius, having allegedly poisoned her second husband Gaius Sallustius Crispus Passienus. She had also arranged the deaths of Caligula's third wife, Lollia Paulina and Messalina's mother Domitia Lepida the Younger. She saw that the dynasty's numbers dwindle with the execution of Marcus Junius Silanus Torquatus, a grandson of Julia the Younger, to strengthen Nero's claim, having previously arranged
Agrippina the Elder to Augustus, a significant factor in the marriages of the emperors and princes of the dynasty. The Annals repeatedly has Agrippina competing for influence with Tacitus simply because she is related to Augustus biologically. Tacitus presents Agrippina as being kindred to aristocratic males, and has her reversing gender roles, which showcases her assumption of male "auctoritas" ("authority") with metaphors of her dressing and undressing. In an example of Agrippina assuming "auctoritas", he says: Using the above epithet, ""(femina) ingens animi"" ("..[a woman], great for her courage"), he assigns a haughty attitude to Agrippina that compels her to explore the affairs