Beauty and the Beast - How has your muse changed as a person over their life? Have they changed for the better or for worse?
I’d say Kenny changes a lot as he grows up, but it’s not super noticeable or significant (from others’ perspective) until he’s an adult.
See as he enters into being a teenager he comes to accept he’s never going to outgrow this stupid curse, and decides if he’s never going to actually die he’s going to live life to its fullest and take advantage of that fact. He simultaneously becomes selfish and altruistic; snarky and friendly; open and reserved. The hints of contradictions he showcases in childhood become a lot more pronounced. Chances are, if you aren’t close to him, you aren’t seeing him at his core.
It’s not until he’s an adult and fully realizes his maturity and how much of a, well, an asshat he’s being, in some ways, that he decides to... chill. He decides to help people, really help them, which is why he opens the center. He still moonlights as Mysterion to tackle problems diplomacy and Kenny can’t, and because he still has that “gift,” so he damn well better use it.
Kenny’s growth is all about realizing the universe has been making him its bitch for years, but now the tables can turn and he can make the universe his bitch.
Faux confidence, cheer, optimism and content become real... to the extent they can be, when cursed with brutal immortality.