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The Seventh Sister was a Mirialan Inquisitor tasked by Darth Vader to track down the Rebels and capture any surviving Jedi Knights. She was specifically tasked with eliminating or capturing Ahsoka Tano, as well as her allies, and had several encounters with the rebels before she was finally slain by Maul on Malachor.
After the Grand Inquisitor's death, all of the Inquisitor's were assigned to track down the Jedi. The Seventh Sister arrived at an Old Republic Medical Station and teamed up with the Fifth Brother against the Rebels. They managed to capture Ezra Bridger and later Sabine. Garazeb Orrelios and C1-10P rescued the pair from their clutches and the Rebels escaped.
The Seventh Sister was later assigned to track down force-sensitive infants for her master Darth Vader and this led her and the Fifth Brother to various planets. On Takobo, Kanan Jarrus, Chopper, Ezra Bridger and Garazeb Orrelios managed to save two children from them. The Inquisitor's pursued the escaping Rebels but were met by Ahsoka Tano who dueled them. They were both defeated by the former Jedi but were rescued by Stormtrooper reinforcements. Ahsoka escaped in the Phantom with the other Rebels. A probe discovered that the Rebels were hiding on Garel and the two Inquisitors made plans to attack them.
They put their plan into action and attacked Garel with Agent Kallus but failed to keep them from escaping.
The Seventh Sister and the Fifth Brother continued to find Ezra and Kanan wherever they went, duelling them on several planets. Ahsoka traveled with them to the Lothal Jedi Temple to try and connect with Master Yoda. The two Inquisitors arrived and used the force to open the temple. Once they arrived inside, the Jedi had gone and a vision of the Jedi Temple Guards led by the Grand Inquisitor attacked them. Darth Vader later arrived and met with the duo, impressed with their discovery of the temple. The Fifth Brother told him that the Jedi were growing in their power but Vader told them that it would be "their undoing".
The Seventh Sister and the Fifth Brother were sent to Malachor and found Kanan Jarrus and Ahsoka Tano with the Eighth Brother in captivity who they quickly freed, duelling the Jedi. Ezra Bridger exited the nearby Sith Temple with Darth Maul and the Seventh Sister was surprised to find that the legends were true and that Maul was still alive. The Inquisitors asked wether Maul had the Holocron they had come for but he wouldn't give a direct answer as he worked with the Jedi against the them.
The trio fled but the Eighth Brother left them to attack the Jedi. The Fifth Brother began to follow but she stopped him explaining that they would attack afterwards and succeed.
The Jedi and Maul were traveling up the temple as Maul had told them that the vault at the very top would unlock the secrets in the Holocron. When the Eighth Brother's attack fails, the Fifth Brother joins him and they attacked Kanan and Ahsoka while the Seventh Sister attacked Maul and Ezra. Eventually Maul called on the Force and pulled her off the ground, commanding Ezra to kill her. Ezra finally refused, forcing Maul to throw his lightsaber which killed her instantly.