For an individual character probably either Atlas or Zero. I'm gonna talk about Atlas though, because I feel like I've talked about Zero in this thread before.
Spoiler for mental health struggles/especially anxiety, just to be safe.
I originally created him as a vent character when I was a teenager and back them basically his only personality trait was anxiety. Like. Atlas existed to run around panicking. Now, with time I have changed and so have my characters, but I thought a lot about Atlas in particular after writing him in a forum game for the first time because my inner response was just: Hell no. (I still feel sorry for that post oops.) He is very dear to me but that moment I realized that I can not stand that version of him so I thought a lot about what makes sense for him and how I could change him in a way that is still in character but more bearable basically. So he still has anxiety, but he also has an actual personality and is more self-aware. Still in denial, but deep down he knows himself. (Because that was another thing... what semblance of a personality he had made no sense, since it walked a fine like between being too nice and getting used and being psycho. Because well, he was edgy. Still is. but to a lesser degree.)
TL;DR old vent character got an actual personality and is now self-aware because I couldn't stand him anymore.