A Jedi Padawan during the time when Obi-Wan Kenobi was a Padawan in the Temple as well, they were very good friends by the time they were both ready to be apprentices in the field.  Siri was apprenticed to Master Adi Gallia, a high-ranking Council master, shortly after Kenobi was apprenticed to Master Qui-Gon Jinn.  However, she showed signs of loving fighting more than Jedi should, and this would eventually lead to her demise.  Rather abruptly after the Battle of Naboo, Siri Tachi abandoned the Jedi Order after a violent disagreement with her Master while they were tracking smugglers on the Kessel Run, and became a worker for Krayn, a slave trader within the Republic.