Danaan Kerr was a Jedi Knight of the Old Republic serving the order during the time of the Clone Wars. When Darth Sidious initiated the Jedi Purge with the help of Darth Vader, Kerr went into hiding. He was discovered soon after however and brought before the two Sith lords. Rather than kill Danaan, Palpatine allowed him to live as he sensed Kerr's inclination towards the Dark Side. In the years that followed the revenge of the Sith, both Palpatine and Vader sought out Force-sensitives and former Jedi in hopes of twisting them to the Dark Side and using them for their own, dark purposes. While they did not enlist Kerr into their service, they did allow him to live and grow stronger which would in turn be of service to the Dark Side itself.
Left to his own devices, Danaan Kerr was consumed completely eventually becoming a consummate Dark Jedi. With the deaths of Palpatine and Darth Vader, Kerr retired to the planet of Rannon in the Valley of Ternaax to live out his days as an old hermit rarely disturbing others. Years later, rumors spread that Palpatine had returned to the galaxy and this news rejuvenated Kerr's dark proclivities. He began to use his powers to subtly influence and terrorize the citizens of Rannon. He even took a number of apprentices under his tutelage and trained them in the dark arts. As the dark side manifested itself around Kerr, the lush valley in which he lived became rotted and evil.