what is the true self?

Not true self. I meant ultimate self.. what is the definition of ultimate self?

Potential. Could-have-beens. The Ultimate Self is the concept of a character at the core of a character. Taking it more Metatextually, for example, at the end of the comic Jade is the Jade that saw John and Davesprite die when LOWAS blew up. But Jade’s Ultimate Self is the idealized version of everything that Jade has ever done in canon, and her potential for growth and doing stuff.

Take Terezi for example, who’s one of the most visible examples of this concept. She… Struggles with her choice. Because she doesn’t see what she could’ve done to save Vriska. Then John gives her the chance to undo it, and fixes her mistake. The new Timeline Terezi, however, struggles with NOT having undergone this growth, and never being able to quite reach the ideal GO! Terezi set for her, and never quite feeling she could measure up to Vriska. So she uses her Mind Powers to vicariously… See this Choice. These outcomes. What she did. What she could’ve done. What she didn’t do. And all of that, all of those Timelines, in the end, do affect the growth of the characters, do affect the reader’s perception of these characters, it shows their potential. Terezi most clearly of all characters tries to reach this ‘Ultimate Self’ to feel whole, but ultimately, the Ultimate Self is more of a conceptual amalgamation of what the distilled essence of each Character is.

The Sprites Squared are a good representation of the Ultimate Self though, as they are a literal amalgamation of every iteration of the characters that form them put into one body with obscene knowledge about SBURB and Paradox Space.