Complex sentence: She had once been a Jedi, and a lover of Jedi Lord Kiel Charny, but turned to the dark side, joining the Brotherhood of Darkness, where she quickly climbed the ranks.
Split into simpler sentences: She had once been a Jedi, and a lover of Jedi Lord Kiel Charny. She eventually turned to the dark side, however, joining the Brotherhood of Darkness, where she quickly climbed the ranks.