I created Amber and Vince at age 23. I was still in college (though almost out) and had close connections to high school, with its memories close on my mind. But it's possible that if I did things now, I would have tried to create faculty, with a trans character who isn't so shy about it. But there's something to say about giving Amber actual character by her being unsure of herself and generally introverted. I based a lot of her on me, as I was in high school (though I never had multiple personalities, and as well I wasn't adopted, I'm white and I don't have super powers--sadly), which may be a reason I was able to keep her consistent the entire time. Vince, though, was a complete invention, and he often seemed to be a support for Amber more than his own character, to me.
Of my tertiary characters, I have Grant, whose personality was largely inspired by my older brother (as he's the older brother to Vince), though the others (Just Plum Awesome, Commodore Tatya, Merry Maiden and some others) were just really created as the stories saw fit and were complete inventions. But sometimes such characters can resonate a lot.
Makes me think, I do want to draw up a group portrait of all my superheroes, but that would be gigantic. Still, it would be nice, and maybe I can get the thing made into a poster, or something.
On another note: one thing that can possibly work to shoot lifeblood into the creative veins is to return to the previous stories and read them, remembering how good it was seeing them posted when the boards were lively, especially the RPs. Sure, they often got kind of jumbled, but it was such a process of presenting characters that was great.
All the bad things in life only help you appreciate the good even more.