Mithridates was the eldest son of Mithridates VI Eupator, king of Pontus, and Laodice, whom the king had executed for unfaithfulness. Mithridates "the younger" served his father loyally in the first war with the Roman Republic and suffered defeat at the hands of the Roman commander Gaius Flavius Fimbria at the Rhyndacus in Asia Minor in 85 BC. The younger Mithridates fled to join his father at Pergamon, but both were then chased by Fimbria to Pitane, from where the two Mithridates managed to escape by sea.