Octavius had a sister, Octavia,

Octavius had a sister, Octavia, who had been the wife of a Roman general
named Marcellus. She was a very beautiful and a very accomplished woman,
and of a spirit very different from that of Fulvia. She was gentle,
affectionate, and kind, a lover of peace and harmony, and not at all
disposed, like Fulvia, to assert and maintain her influence over others
by an overbearing and violent demeanor. Octavia's husband died about
this time, and, in the course of the movements and negotiations between
Antony and Octavius, the plan was proposed of a marriage between Antony
and Octavia, which, it was thought, would ratify and confirm the
reconciliation. This proposal was finally agreed upon, Antony was glad
to find so easy a mode of settling his difficulties. The people of Rome,
too, and the authorities there, knowing that the peace of the world
depended upon the terms on which these two men stood with regard to each
other, were extremely desirous that this arrangement should be carried
into effect. There was a law of the commonwealth forbidding the marriage
of a widow within a specified period after the death of her husband.
That period had not, in Octavia's case, yet expired. There was, however,
so strong a desire that no obstacle should be allowed to prevent this
proposed union, or even to occasion delay, that the law was altered
expressly for this case, and Antony and Octavia were married. The empire
was divided between Octavius and Antony, Octavius receiving the western
portion as his share, while the eastern was assigned to Antony.