McFlabbergasty, you're a braver person than I, focusing the prequels on a relatively unknown character to the audience. Heck I deliberately chose to have Bail and Darelda as a major focus, as theoretically the audience would have some level of emotional investment in them given their eventual relationship with Leia. Thus even if you didn't care about them in the context of the story of the film, you could still be interested in seeing what kind of people they were, and thus in a way where Leia got much of herself from.

Wholly original character HX-81 I included somewhat out of the sheer novelty of having a droid (particularly a battle one) with a very distinct personality to 3PO and R2.