MARA JADE

Born to Jedi parents who were killed by Sith lord Darth Vader when she was only a few days old, Mara Jade was taken to Coruscant where she was trained in espionage, weapons and most importantly of all, the Dark Side of the Force.
Just before the Battle of Yavin she passed her final trials and became the Emperor's Hand - assassin and spy who answered only to Emperor Palpatine himself.
During the Battle of Endor, Mara was on Coruscant and was unable to protect her master from the Jedi who destroyed him. Upon his death the Emperor sent an order to Mara - kill Leia Organa (who later became Skywalker) even though it was really Council Member Adi Gallia who struck the death blow.
Mara met Leia for the first time on Chakran where they came to a stalemate. Their next encounter was on Yarori where again Jade was unable to make the final move. Mara felt the influence of Emperor Thrawn was playing to much on her and faked Leia's death in order to kill her in her own time but soon she began to develop feelings for the princess.
After the defeat of the Empire at Yarori Mara was forced into the slums of Coruscant hoping to escape and fulfil her promise to her dead master - she will kill Leia no matter what.