Star Wars: Every Sith Who Turned To The Light Side

Quinlan Vos was a Jedi Master with the power of retrocognition. This talent allowed him to observe people's memories through physical contact, which allowed him to become a master tracker. He regularly used this ability to infiltrate criminal dens and destroy them from the inside.

After Asajj Ventress abandoned the Sith, she convinced Quinlan to help her hunt down Count Dooku, better-known as Darth Sidious' apprentice, Darth Tyrannus. Due to Dooku's astounding power, Ventress believed Quinlan didn't have a chance against him unless he was taught in the ways of the Dark Side. Quinlan and Ventress became close during this period and eventually fell in love.

Although the young Jedi intended to use the powers of the Dark Side for good, he was corrupted and joined with the Sith. Fortunately, Quinlan's love for Ventress helped him find his way back to the Light Side.