I'm wondering the reasoning behind choosing Amathyst?

classic examples of lack of identity in several episodes (having to do a quiz on personality traits, “im just a mistake to you”)

associating things very strongly with the self: “this is like, my entire existence!/i didnt ask to be made this way!”

finding personality strengths from companions: steven and amethyst fusion in particular

Aw shit if I had known you were there I would have said HAI! I went the whole weekend