WARNING: Some SPOILER topics ahead, which may be problematic for some who have yet to catch the finale. PROCEED WITH CAUTION!
It could be argued that bringing Darth Vader front and center to a show only in its second season might present some logistical issues. The show takes place in a generally unillustrated period between Vaders fiery, crispy birth in Episode III: Revenge of the Sith and his violent interrogation aboard the Tantive IV in Episode IV: A New Hope, and the Sith lord's path is pretty well set, as are the attributes which define him. However, this show seems to be quickly heading in a direction regarding the formation of the Rebellion that doesnt leave much time to beat around the bush. Vader needed to be on show. Now. And there are plenty of things into which Vader can be squeezed without disrupting the immutable state of his being in the Original Trilogy films.