I think Pluto Lochlyn Westhouse means as much to me as she does because she's not just a representation of myself, she's a good representation of why I write myself into stories in the first place, instead of just creating someone else. First, she started off as vaguely nonbinary coded. She became nonbinary with me. And now, writing the fourth (and likely final, since I know eventually people will get tired of reading about her) book and getting ready to clean up the series for AO3, time travelling insanity and all, she's going back to being a fully female character. Because I realized there's a lot of male characters I can identify with and whose story arcs I like, but I've met exactly one (1) female character I see myself in who's not treated ickily by the narrative in one way or another, and/or made into something at the end that I don't want to become. And that disparity, and the reasons for it that I've uncovered over time, drove me crazy enough I felt I had to do something about it.
And that's why I write myself into the stories: because I learn things about myself over time, both as a person and as a writer, that I wouldn't learn if I wasn't hidden somewhere in the narrative.