Champion is the third and final novel in the Legend trilogy.
Day has sacrificed a lot to stop the corrupt Republic and Elector. With a new elector Day hopes for suitability and change to come to the Republic. Knowing that he holds the power of the common person Day continues to work with June in helping the Republic mend it's broken bond with the citizens. All is going well until Day learns that the experiments the Republic did on him are catching up and he has little time before the side affects will take his life.
June has it all, she is in a position of power, learning how to govern the Republic and close the Aden the current Elector of the republic. Yet everything still feels wrong, June yearns to be near Day who seems to be going out of his way to ignore her. However when crisis approaches the Republic due to the colonies June and Day have no choice to be to unite in an attempt to save the Republic one last time.
It has been several months since I read Prodigy and even longer since I read Legend. I recall I adored legend and was disappointed in Prodigy. That is pretty typical for me when it comes to trilogies however usually the third book redeems the series for me. Champion started to do that for me until the end. I hated the ending, ruined the whole series for me sadly. Despite not liking the ending I would consider reading more of Marie Lu's work.