What was the story of Cleopatra?

She was born in Alexandria, which was at the time was the learning capital of the world, and was the daughter of the king Ptolemy XII, also called Auletes, which means "flute player". Her mother is unknown, but historians assume it was Cleopatra V, a cousin or sister of her father.
By the time Cleopatra was a child, her father's grip on his empire was slipping, and the threat the Romans posed to Egypt's security was too great to ignore. While he and his daughter were negotiating in Rome, Cleopatra's stepmother and her father's second wife, Cleopatra Tryphaena VI, took over the throne.
Shortly afterwards, Cleopatra's older sister, Berenice IV, overthrew Cleopatra Tryphaena VI (many believed by poisoning her) and assumed power over Egypt before being executed by her father (what a lovely family). Cleopatra, age fourteen, then ruled alongside her father until his death in 51 BC. At eighteen years old, she was forced to marry her twelve year old brother, Ptolemy XIII, and was made queen of Egypt.
After a long power struggle between her and her brother, Cleopatra and her younger sister, Arsinoe, were eventually forced to leave Egypt, and her brother became the only ruler.
Around that time, the infamous Julius Caesar, who didn't care much for Ptolemy to begin with, was.... shall we say, "persuaded" by a very convincing Cleopatra to side with her in the plot to overthrow her brother and put herself back on the throne again. Nine months afterwards, she gave birth to their son, called Caesarion, which means "little Caesar". Shortly after Caesar began to back Cleopatra's rightful claim the the title of regent, her younger brother and husband was drowned in the Nile, likely by Caesar's command. She married her even younger brother, and was once again queen.
Cleopatra was in Rome with her lover on March 15th, 44 BC, when the Roman dictator was famously assassinated by a retinue of senators. Her husband and brother died a little while afterwards (many believe his sister poisoned him) and Cleopatra married her son to secure his future.
Shortly afterwards, she met her second lover, Mark Anthony, and their alliance angered Caesar's successor and nephew, Octavian. She gave birth to twins, Alexander Helios and Cleopatra Selene II, and one more boy, Ptolemy Philadelphus, when Octavian attacked Alexandria. During this attack, Cleopatra and and her handmaidens injected themselves with the venom of a snake, causing them to die instantly.

Hope this helped. :)