[Cleopatra II as Isis, 2nd century BCE, source: Wikimedia Commons]
Cleopatra was the daughter of Ptolemy V and Cleopatra I.* We don’t know exactly when she was born, but she probably married her brother Ptolemy VI shortly after her mother’s death in 178/7. The two were incorporated into the dynastic cult shortly thereafter. They had at least four children together: two sons (both named Ptolemy) and two, maybe three daughters (Cleopatra Thea, Cleopatra, and possibly Berenike). After a few years of ruling together they were joined by their younger brother Ptolemy VIII. The three of them didn’t get along terribly well though and tried several times to remove each other from power. When Ptolemy VI fled in 169, it was Cleopatra who negotiated his return. She also supported the construction of a Jewish temple in Alexandria during the Maccabean revolt and, at some point during this portion of her reign, won a victory in the pan-Athenaic games.
Things didn’t quiet down when Cleopatra’s brother-husband died in 145. She continued to rule alongside Ptolemy VIII and eventually married him. In the year 140 or so, Ptolemy decided to marry again and chose his double niece and stepdaughter, Cleopatra III, as his second wife.**
The three ruled as a triumvirate for several years before Cleopatra rebelled against her Ptolemy and Cleopatra III and drove them out of Egypt. She ruled on her own from 130 to 127 before they returned and deposed her, forcing her to flee to Syria, which was ruled by her daughter, Cleopatra Thea, and son-in-law, Demetrios II.
She did eventually reconcile with Ptolemy and Cleopatra III in 124 and returned to rule alongside them once more. After Ptolemy VIII’s death in 116, she ruled briefly alongside her daughter and grandson Ptolemy IX. She died in the early months of 115 BCE.
*Probably. She was definitely Ptolemy V’s kid, but there’s no direct evidence that she was also Cleopatra’s. All of the indirect evidence points to it though, since she was almost certainly legitimate and Ptolemy V never married any woman other than Cleopatra I.
**Some people claim he divorced Cleopatra to marry her daughter. Others say he was married to both of them at the same time. Since the only evidence for a divorce is the fact that he married again and since polygamy was a known practice among Hellenistic kings, I’m inclined to assume the latter.