Honestly all of my characters end up less extreme over time, which is more "realistic" but sometimes quite a bit less fun. Sorley I think lost the most in becoming a POV/major character- they are less aggressively weird and off-putting and have many more worries than I thought they did. Casey became inundated with anxieties and is getting far more frustrated with and judgemental of people than he was ever meant to. He's also ended up more theatrical and with much more interest in fashion and other arts than I thought he would, but that's fun! Marie is simply less mean and more weird, but unlike the other two I think I like her better this way haha. I'm sure more about them has changed but that's my core three and the major ways they have!
Ciecro upon first writing was a "muscle for brains" punk.
Now, he's a distant, but clearly giving a muk friend who focuses on being strong and capable, while also a hard worker in what he aims for despite the drives for those reasons being obstacles he will have to grow to face in himself.
...Tl;Dr: essentially, becoming an actual character.
“A friend is someone who understands your past, believes in your future, and accepts you just the way you are.”
The protagonist in my novel goes through some really harrowing experiences and they definitely change him. He starts off as someone running away from his problems - the crushing weight of expectations he can't live up to primarily - and is really wrapped up in himself and those issues. He matures a lot over the course of a few days. He becomes aware of his own strengths and weaknesses, he becomes more empathetic and he learns that he can choose his role models and who he wants to become. He's also greatly traumatised, but instead of fleeing from those issues, he's working on coming to terms with what he experienced. For a less intentional aspect, I originally conceptualised him as a bit more of a dick than he ended up actually being.
For my fic here that I swear I will actually update again one day... that's a bit trickier honestly. I've written a fair amount but it's comparatively still fairly early in the story. The characters are only just beginning their real growth. Eloy's definitely changing a bit, he's gotten less cocky and more willing to reach out to others for advice and to learn from his betters. Layla's become a little less abrasive and Gwen is just starting to become a little more sure of herself and confident in who she is. Niall... he's at the very beginning of a darker path. Lauren has remained pretty static, but she's enters the story having already gone through a lot of growth in her life. She's almost more of a mentor character. No real unintentional shifts with this bunch.
I might come back again later once more and drop some tidbits about the way some favourite text RP characters or the characters from the book I'm working on right now have evolved too. Some of the former group have grown a lot while the latter group have gone through a lot more revisions on who they are compared to their predecessors.