Nero had become Emperor at seventeen, the youngest emperor until this time.
Ancient historians describe Nero's early reign as being strongly influenced by his mother Agrippina, his tutor Lucius Annaeus Seneca, and the Praetorian Prefect Sextus Afranius Burrus, especially in the first year.
Other tutors are less often mentioned, such as Alexander of Aegae.
Problems arose very early in Nero's rule from competition for influence between Agrippina and Nero's two main advisers, Seneca and Burrus.
Agrippina had tried in 54 to sit down next to Nero while he met with an Armenian envoy, but Seneca had stopped her and prevented a scandalous scene (as it is unimaginable at this time for a woman to be in the same room as men doing official business).
Nero's friends also mistrust Agrippina and tell him to beware of his mother.
Nero is reportedly unsatisfied with his marriage to Octavia and enters into an affair with Claudia Acte, a former slave.
In 55, Agrippina attempts to intervene in favor of Octavia and demands that her son dismiss Acte.
Nero, with the support of Seneca, resists the intervention of his mother in his personal affairs.
With Agrippina's influence over her son severed, Nero has become progressively more powerful, freeing himself of his advisers and eliminating rivals to the throne.
One of Agrippina's favorites, the freedman Pallas, is sacked in early 55 from his job as secretary of the treasury—a post he had held since the reign of Claudius.
According to Tacitus, Agrippina reacted violently to this slight by Nero.
She declared that she repented of her actions to bring Nero to the throne, and would throw in her lot with Britannicus, the true heir who would soon come of age.
She threatened to take the boy to the Praetorian camp, where she would admit to murdering Claudius and Britannicus would be declared emperor.
Nero does not take this threat lightly.
Tacitus recounts Nero's numerous attempts to publicly undermine Britannicus' image.
One such attempt was when Nero asked Britannicus to sing at a drunken party, months before his fourteenth birthday.
Britannicus however, not only avoided humiliation, but also generated sympathy among the guests, after singing a poem telling the tale of how he had been cast aside in favor of Nero.
Tacitus also stated that a few days before his death, Britannicus was sexually molested by Nero (Tacitus Book XIII, 17).
According to Tacitus, Nero moved against Britannicus, employing the same poisoner, Locusta, who had been hired to murder his father, Claudius.
Earlier in 55, Locusta had been convicted of poisoning another victim.
When Nero learns of this, he sends a tribune of the Praetorian Guard to rescue her from execution.
In return for this, she is ordered to poison Britannicus.
The first dose fails, and Nero decides to throw caution in the wind.
Britannicus is poisoned at a dinner party attended by his sister, Claudia Octavia, Agrippina, and several other notables.
The first-century chronicler Suetonius wrote that the assassin avoided being given away by a food taster by adding the poison to his drink when Britannicus asked for it to be cooled, as he felt it was too hot.
The substance was instantly fatal, and Britannicus fell to the floor foaming at the mouth.
He dies on February 11, 55, one day before his fourteenth birthday, less than a month before he is to assume manhood, and just four months after his father's death.
Nero dismisses the murder by claiming that the boy had suffered from epilepsy.
Some modern historians, particularly Anthony Barrett, suggest that he may have indeed suffered from the disease, and that a particularly bad seizure killed him.
After the death of Britannicus, Agrippina is accused of slandering Octavia and Nero orders her out of the imperial residence.
According to Tacitus, Nero protected Locusta by granting her immunity from execution, rewarding her with a vast estate and even sending students to her.
According to Suetonius, Britannicus had been good friends with the future Emperor Titus, whose father Vespasian had commanded legions in Britain.
As part of the Flavians' attempts to link themselves with the Julio-Claudians, Titus will claim that he had been seated with Britannicus on the night he was killed.
He even claimed to have tasted the poison, which resulted in a serious and long illness.
Titus will go on to erect a gold statue of his friend, and issue coins in his memory.
Tacitus states that from this moment Octavia became very unhappy, but learned to hide her affections and feelings around her husband and stepbrother.
