Why did Mark Antony marry Octavia, the sister of Octavian?

Mark Antony married Octavia, the sister of Octavian (later the emperor Augustus), primarily as a political move to solidify an alliance between the two leaders.12

Following the death of Antony's wife, Fulvia, and the reconciliation between Antony and Octavian at Brundisium in 40 BCE, the marriage served to reduce tensions and seal the pact that divided the Roman world between them. This union helped stabilize their joint rule as triumvirs, as Octavia was instrumental in maintaining peace between her brother and her husband, notably facilitating the Treaty of Tarentum in 37 BCE.31