Shakespeare has quite a few usurper/usurpee pairings: Macbeth and Malcolm, Frederick and Duke Senior, Claudius and Hamlet, Antonio and Prospero, Richard III and Edward V, Bolingbroke and Richard II. Richard II comes closest to challenging the stereotypes, with Richard and Bolingbroke both having their fair share of faults and virtues, and a relationship best summed up as "It's complicated". Hamlet, as I've frequently maintained, gives us Shakespeare's greatest villain in its title character, which is an interesting variation, and Malcolm at least conducts a thought experiment with Macduff in which he asks whether he would still be worth supporting if his character were worse than Macbeth's - the conclusion being that he would not. But that contingency remains in the realm of the hypothetical.
But it's not to Shakespeare that we should be looking for a serious interrogation of this topos. It's to the republican writers of fantasy and romance, surely? And particularly to those writers who like inverting fantasy cliches for fun. But here's where my lack of reading (and possibly memory) shows up. Where are the stories in which an evil True Heir attempts to take back the throne from a good usurper? I don't think Diana Wynne Jones ever attempted this kind of inversion, exactly - did Terry Pratchett? Did anyone? And if not, why not?