Morrun Dokaas is a fictional Sith and Revanite developed by BioWare for the MMORPG Star Wars: The Old Republic. Tari Darkspanner recognized the strength Morrun Dokaas had with the Force, so she trained him as her apprentice, even though training a Chagrian as such Morrun was against the norms of the Sith Empire.
For decades, I have served the Master. He found me when I was a larva and saw that I was strong in the Force.
Against the Empire's traditions, he trained me. This is the way of Revan – to teach all species the path to power.— Morrun Dokaas, in Star Wars: The Old Republic
Why do you think Revan trained aliens in the ways of the Sith? Why did Revan offer power to all seekers?
[It gave him an edge.] Revan knew that servants are more useful when they're powerful.
[It was just.] He believed everyone should have the chance to aspire to power.
You answer well. You answer wisely. You speak like a true Revanite.
Your answer is not my answer. But it is… sufficient. It is worthy of a Revanite.— Morrun Dokaas and the player, in Star Wars: The Old Republic
Never forget that Revan was Sith. And there is no kindness among the Sith.— Morrun Dokaas, in Star Wars: The Old Republic