Banestone

Banestone didn't worry about a complicated backstory or motivations. He was just a BADASS.

Tall, thick, and ebony-skinned alien Sith from the Sith Order, Banestone arrived in an egg shaped ship named The Shell from the edges of the universe. He was a cybernetic being, almost half of him consisting of droid parts. He had a droid right arm and left leg, and his droid arm opened up to store his lightsaber (Like Robocop holstering his gun inside of his leg). His droid hand also had two very small lightsabers built into the back (called lightblades) like claws.

Deep in the recesses of the newly-constructed Sith Order palace's hangar, Banestone walks up to a tall, egg-like red ship; which is standing tall and aloof upon unformed prongs to keep it stable. His mysterious craft unforms a hatchway and ramp as it senses the bulky Sith's approach, and Banestone continues into The Shell without even needing to check his stride. With the soothing hums of the onboard generator and ship's computer in his cybernetically-enhanced ears, he drifts slowly to one side of the continuous round wall and eases into the hard but perfectly-fitting bed that unforms noiselessly from it. His gleaming full red eyes dim slowly and his lids close over them as he comfortably goes to sleep... the first chance he's had to do that in a while.

Banestone was a scout from a warrior race that had begun to consider expanding from the Unknown Regions into what THEY considered unknown regions. That was never pursued; Banestone simply decided that these new parts of the galaxy were much better than where he came from and abandoned his race (After all, they wouldn't come looking for him if they thought that even their best warrior and best ship couldn't make it back).

Eventually he left The Sith Order, and continued exploring the galaxy, taking on an apprentice, Kar'h'tzen Shaed. Banestone did train Shaed brieflyending when Shaed got bored of Banestone's reluctance to continue with the Dark Side, and left him to the other Sith that he'd found out about from Banestone. He found Lilaena De'Ville, who took him as an apprentice and then they went back to find Banestone and collapsed a cave on the cybernetic Sith. Banestone did survive, but it's mostly unwritten knowledge that he became a Jedi after that -- in all but name; he simply abandoned the Sith and the Dark Side and made no attempt to contact or join the Jedi, and wandered around trying to redeem himself on his own terms.