Okay, so after looking at it very closely, here's basicly what I've come up with. Legacy is basicly a Deconstructor Fleet for Star Wars. For example the characters mostly some kind of composite of characters seen in the films, with an extra layer of deconstruction added on top:
Cade Skywalker= Luke Skywalker, Han Solo. Basicly he combines the two staple Star Wars protagonists, the outlaw, and the Jedi chosen one. The Deconstruction comes into play in a few key areas. First he has the Han Solo apethetic veiw on life. However unlike Han, this isn't flat earth atheism, it's an aquired bitterness, making it all the more profound. His drug addiction shows just how seedy the life of an outlaw can be. Unlike Luke he didn't jump at the call. He spends his whole life trying to hide from it. Unlike Luke's relationship with force ghost Obi Wan, Cade openly mocks and be-littles his ancestors.
Nyna Calixte= Darth Vader, Tarkin, Prequel era Palpatine. Like Tarkin she's an utterly ruthless high ranking Imperial officer willing to commit terible actions to meet her goals, beleving firmly that she's doing what's best for the galaxy. Like Prequel Palpatine, she's a Chess master, carefully trying to manipulate evens behind the scenes. Like Vader, the fact that she's Cade's Mother is a major plot twist. However, unlike Palpatine, who was allways thirty steps ahead, she is actually out manuavered by the Sith and spends most of the series plotting against them. It could be argued that she's even more of tragic monster then Vader, as she's constantly struggling between her plans, and the safety of her son.
The roll of Leia is spilt between two characters. Marasiah Fel, and Gunn Yage. In the original trilogy Leia is the princess of Alderan, a world that, in her own words is "peaceful" and "has no weapons". Marasiah on the other hand is the heir to the Fel Empire, the ones who started the war. Gunn is the other half of Leia. The sister the hero never knew he had. She also has elements of the X-wing pilots from the original trilogy. However she is on the Imperial side. This is key for a number of reasons. The original rebel pilots all had unique personalities, and a lot of character devolopment, conversly however, a lot of effort was taken to dehumanize their enemies. The TIE fighters didn't have a hyperdrive, or their own life support systems, leaving the TI Es completly reliant on their Star Destroyer. The pilots themselves didn't have faces, and where established to be clones. While the Rebel pilots all had emotional atachments to their fighters, each of which was unique due to repair and costumization, where as the Imperial pilots probably never used the same ship twice. The Imperial Knights are also an Interesting concept, allowing he exploration of one of the biggest flaw in the Old Republic Era Jedi, the conflict between political loyalities and their duty to the force is something almost every character in the Imperial Knights has to come to terms with. The biggest thing however has to be the introduction of shades of grey to a setting that up until this point has always been about the conflict between the light-side and dark-side.