Yoooo you read Graceling!!!! I just recently reread Bitterblue, remembering nothing about it beforehand, and I was floored by its amazing depiction of abuse/gaslighting. I never would have thought to represent gaslighting as an evil superpower. Using it to support the plot of a political mystery novel is just so cool.
I fully agree. Normally I'm not a big fan of characters having had their memories changed, since it risks giving the author a little too much license to straight-up lie to the reader to conceal information, and/or introduce a world with no internal logic at all which doesn't make for an enjoyable story.
BUT that's clearly not what Cashore is doing with Bitterblue. Instead, that plot is so clearly about propaganda, about how history becomes story and what's lost along the way, and about how a "hero" is in the eyes of the people who benefited from that hero's violence. Like, are George Washington and Theodore Roosevelt and Thomas Jefferson heroes? It sure as heck depends on whether you ask a white person, or a Black or Native American one. Human memory is short, history is malleable. People in power can edit the past.
Are you a butcher or a great warrior? Are you a freedom fighter or a terrorist? Depends on who's telling the story and how. The fantastical interpretation in Graceling is clearly Cashore pulling the classic SF trick of taking something figurative and making it literal, and asking a lot of fascinating questions about the responsibilities of leadership along the way.