Since KOTOR (the comic) came out I have been looking for connections to the games they are based on. After reading KOTOR: Commencement I have come to believe that Lucien Draay is Darth Sion. Here is why:

The Meaning of Sion
All Darths have an alternate meaning to their name. Sion's could be it's the English word scion meaning heir, heir to the Sith legacy, both Revan and Malak's the True Sith's. Draay himself is a "scion of an important family," as Vandar says to Zayne in issue 4. Scion is not an often-used word so I doubt that the author just picked it up off the top of there head.

Seen From a Certain Point of View
They have the smae build and they both use similar fighting stances. Imagine a bald Draay and you will see a close resemblance to Sion.

Clothes Make the Man
They have similar fashion sense. Both were a dark cummberbund. Both's clothes have ornate designs on them.

Behind Every Great Man...
Both men also answer to a woman, possibly the same one.