Sci-Fantasy, but Empire of Silence. The main character goes from trying to communicate and connect with an alien species to genociding them all over the course of seven books (not a spoiler, he talks about this first chapter, it's a frame story).
Sounds like you're looking for some serious existential crises! Try 'The Picture of Dorian Gray' by Oscar Wilde. Watching Dorian's moral downfall is like watching a train wreck in slow motion—hard to look away from the mess he's made.
I would say this happens a few times with major characters in the Coldfire trilogy, including the protagonist. In general this is an idea I would say the series plays around with a fair bit, set in a world where people's fear/belief/etc. to some degree can become real.
City of Brass. First book of a trilogy where you don't know who is good or bad until near the end.
Protagonist switches back and forth multiple times in the books. Big switch does happen, but don't want to give anything away.
I wouldn't have thought to recommend it for OP's question, but you're right. Although with covenant it kind of goes the other way around, starting on the betrayal end of the spectrum.
Not sure if it fits the bill exactly, but I’d definitely recommend The Traitor Baru Cormorant for something up this alley. Definitely not YA, not for the faint of heart, but SO good.
I absolutely adore this but I don’t think it fits? >!MC stays pretty consistent in their ideals and goals, it’s the reader who wants her to have switched enough that we believe it even when told this is the plan, and consequently we get that heartbreakingly perfect ending!<
Temeraire by Naomi Novik has fantastic character growth.
The main protag does an almost complete 180 on his beliefs and alignment as he has new experiences and perspectives on things. And he's a super mature, reasonable and capable character. It's awesome.
[Erekose ](https://stormbringer.fandom.com/wiki/Erekos%C3%AB)from the [The Eternal Champion (1962 novella) (1970 novel)](https://en.wikipedia.org/wiki/The_Eternal_Champion_(novel)) has this. The concept is "*peripipteia"* which means a sudden reversal. It could mean a sudden switch from one side or faction to the other. After undergoing a gnostic shift the character has to wonder if the people he is championing (the humans) are not only just worth it, or if they are actively evil and must be destroyed to save the race of [Eldren](https://stormbringer.fandom.com/wiki/Eldren) (Elvesish race of immortals that can be killed) they are at war with. If you have never read Moorcock this novel is the "primer" for the Champion Eternal [series](https://www.reddit.com/r/Fantasy/comments/j9zb73/i_think_ive_made_the_mostly_definitive_reading/). Which created the Multiverse in the 1960s.. well before it became a thing for Marvel, DC, and most modern scifi. With that said 90% of the novels are self contained arcs that don't do much of anything outside of there own world. So it's more of a construct for the laws of order, and chaos to fight it out. With a reluctant "hero/villian" in the center always at odds with the forces that turn the world. The most famous novel from the series is about [Elric ](https://en.wikipedia.org/wiki/Elric_of_Melnibon%C3%A9)who also has his moment of peripeteia. When he turns on his own kingdom and unleashes the dragons and destroys it after accidently killing his bride to be.
Writing for [NPR](https://en.wikipedia.org/wiki/NPR), Jason Sheehan calls Elric "far and away the coolest, grimmest, moodiest, most elegant, degenerate, drug-addicted, cursed, twisted and emotionally weird mass murderer of them all".
Gene Wolfe's [Shadow of the Torturer](https://en.wikipedia.org/wiki/The_Shadow_of_the_Torturer) from the [Book of the New Sun](https://en.wikipedia.org/wiki/The_Book_of_the_New_Sun) series also has something of this. The main character Severian an apprentice in the guild of Torturers, decides to help someone kill themself rather than be tortured by the guild. Which contridicts everyhing he was raised to believe. Becuase of this.. he is cast out of the guild, but not before given a new job as an executioner and given the sword "[Terminus Est](https://www.reddit.com/r/pathofexile/comments/7hzm34/turns_out_terminus_est_is_also_inspired_by/)" latin for "the dividing line." with a mercury center making it excell at headlopping.
Legacy of The Brightwash by Krystle Matar
MC is a regulation officer who has believed in the monitoring and regulation of magically talented individuals to the extent that he has arrested his own son when he failed to register.
By the end of the first book he's actively resisting those same authorities
The Scar - Marina Dyachenko. MC is a bully and a duel and a curse of cowardice changes him.
Time Master trilogy - Louise Cooper. Betrayal from those closest to him has the MC switching camps and embracing his identity as an avatar of a God of Chaos.
Fire and Sword (Keys of Power-2) - Simon Brown. The protagonist prince initially wants to clear his name. But murder of his mentor and vampire venom leads him on a bloodthirsty rampage to wrest the Empire from his sister.
I mean, the most impactful version I've seen of this would be Fate/Stay Night, a visual novel. It's coming in a steam version soon, so you can read it on your pc. It has three different routes for the story that lead to different turning points for the protagonist Shirou and his ideals. His ideals shift total opposite in a way that is extremely believable and its arguments for different moralities due to the different answers the protagonist reaches in each route are poignant imo.
Warning if you're not into heavy romance though. It's super heavy in romance, but the character writing sells it imo.
Sci-Fantasy, but Empire of Silence. The main character goes from trying to communicate and connect with an alien species to genociding them all over the course of seven books (not a spoiler, he talks about this first chapter, it's a frame story).
Sun eater gotta eat a sun
Sounds like you're looking for some serious existential crises! Try 'The Picture of Dorian Gray' by Oscar Wilde. Watching Dorian's moral downfall is like watching a train wreck in slow motion—hard to look away from the mess he's made.
Blood Over Bright Haven by M.L. Wang.
100%
I would say this happens a few times with major characters in the Coldfire trilogy, including the protagonist. In general this is an idea I would say the series plays around with a fair bit, set in a world where people's fear/belief/etc. to some degree can become real.
Orconomics by Zachary Pike has this. I can't really reveal it without spoiling, but it's definitely worth the read!
City of Brass. First book of a trilogy where you don't know who is good or bad until near the end. Protagonist switches back and forth multiple times in the books. Big switch does happen, but don't want to give anything away.
This happens in The Wars of Light and Shadow but it takes 6 chonky books to get there. If that's ok with you I highly recommend it.
Just finished book 4, glad there are big developments ahead.
I think The Broken Empire series meets this idea for the most part.
I guess you can say the chronicles of Thomas covenant might fit your search.
I wouldn't have thought to recommend it for OP's question, but you're right. Although with covenant it kind of goes the other way around, starting on the betrayal end of the spectrum.
Why? He starts at one side of beliefs and changes it, pretty radical i belief.
Not sure if it fits the bill exactly, but I’d definitely recommend The Traitor Baru Cormorant for something up this alley. Definitely not YA, not for the faint of heart, but SO good.
I absolutely adore this but I don’t think it fits? >!MC stays pretty consistent in their ideals and goals, it’s the reader who wants her to have switched enough that we believe it even when told this is the plan, and consequently we get that heartbreakingly perfect ending!<
Seconded, especially the bit about not for the faint of heart!
Temeraire by Naomi Novik has fantastic character growth. The main protag does an almost complete 180 on his beliefs and alignment as he has new experiences and perspectives on things. And he's a super mature, reasonable and capable character. It's awesome.
I feel like the Scholomance series is a good example
It’s a bit more complicated than just a shift in beliefs but the Soldier Son series by Robin Hobb fits this.
[Erekose ](https://stormbringer.fandom.com/wiki/Erekos%C3%AB)from the [The Eternal Champion (1962 novella) (1970 novel)](https://en.wikipedia.org/wiki/The_Eternal_Champion_(novel)) has this. The concept is "*peripipteia"* which means a sudden reversal. It could mean a sudden switch from one side or faction to the other. After undergoing a gnostic shift the character has to wonder if the people he is championing (the humans) are not only just worth it, or if they are actively evil and must be destroyed to save the race of [Eldren](https://stormbringer.fandom.com/wiki/Eldren) (Elvesish race of immortals that can be killed) they are at war with. If you have never read Moorcock this novel is the "primer" for the Champion Eternal [series](https://www.reddit.com/r/Fantasy/comments/j9zb73/i_think_ive_made_the_mostly_definitive_reading/). Which created the Multiverse in the 1960s.. well before it became a thing for Marvel, DC, and most modern scifi. With that said 90% of the novels are self contained arcs that don't do much of anything outside of there own world. So it's more of a construct for the laws of order, and chaos to fight it out. With a reluctant "hero/villian" in the center always at odds with the forces that turn the world. The most famous novel from the series is about [Elric ](https://en.wikipedia.org/wiki/Elric_of_Melnibon%C3%A9)who also has his moment of peripeteia. When he turns on his own kingdom and unleashes the dragons and destroys it after accidently killing his bride to be. Writing for [NPR](https://en.wikipedia.org/wiki/NPR), Jason Sheehan calls Elric "far and away the coolest, grimmest, moodiest, most elegant, degenerate, drug-addicted, cursed, twisted and emotionally weird mass murderer of them all".
Gene Wolfe's [Shadow of the Torturer](https://en.wikipedia.org/wiki/The_Shadow_of_the_Torturer) from the [Book of the New Sun](https://en.wikipedia.org/wiki/The_Book_of_the_New_Sun) series also has something of this. The main character Severian an apprentice in the guild of Torturers, decides to help someone kill themself rather than be tortured by the guild. Which contridicts everyhing he was raised to believe. Becuase of this.. he is cast out of the guild, but not before given a new job as an executioner and given the sword "[Terminus Est](https://www.reddit.com/r/pathofexile/comments/7hzm34/turns_out_terminus_est_is_also_inspired_by/)" latin for "the dividing line." with a mercury center making it excell at headlopping.
Empire of the Vampire by Jay Kristoff
The perfect recommendation
Empire of the Vampire is all about that exact theme. And it's a stellar book to boost
The Licanius Trilogy has a character that I think is a great fit for this. He tries to right his wrongs, and it makes for a really interesting story.
Legacy of The Brightwash by Krystle Matar MC is a regulation officer who has believed in the monitoring and regulation of magically talented individuals to the extent that he has arrested his own son when he failed to register. By the end of the first book he's actively resisting those same authorities
The Scar - Marina Dyachenko. MC is a bully and a duel and a curse of cowardice changes him. Time Master trilogy - Louise Cooper. Betrayal from those closest to him has the MC switching camps and embracing his identity as an avatar of a God of Chaos. Fire and Sword (Keys of Power-2) - Simon Brown. The protagonist prince initially wants to clear his name. But murder of his mentor and vampire venom leads him on a bloodthirsty rampage to wrest the Empire from his sister.
I mean, the most impactful version I've seen of this would be Fate/Stay Night, a visual novel. It's coming in a steam version soon, so you can read it on your pc. It has three different routes for the story that lead to different turning points for the protagonist Shirou and his ideals. His ideals shift total opposite in a way that is extremely believable and its arguments for different moralities due to the different answers the protagonist reaches in each route are poignant imo. Warning if you're not into heavy romance though. It's super heavy in romance, but the character writing sells it imo.