guys that purple thaaang will never leave my head. I love him. he is my silly. anyway I shall tell you all the entire backstory behind my purple boy:
As you know, I am very very into warrior cats even now. I was listening to one of Blixemi's songs called "All They See" which is about Tawnypaw/pelt and Bramblepaw/claw struggling under the weight of their father Tigerstar's legacy, and being insecure because their Clanmates will look at them and just see Tigerstar, rather than them as individuals.
I decided that Tawnypaw's part was really fitting for Kyoko because she has an entire line about how her family only saw her as "the little girl who was abandoned by her father" and she constantly had to prove herself to get out of his shadow. I had an imaginary animatic in my head about this. But then I realized: there was nobody to play Bramblepaw's part, and thus I gave her a nameless brother.
The Kirigiri Siblings AU went through a different rendition before the story became what it is today; like Soichiro used to be called Sichiro, they had wayyy more cousins and aunts and uncles in the Kirigiri house, and the ending basically led to the two finding their father again at Hope's Peak Academy. All while Soichiro (or Sichiro I guess) was a supportive non murderous brother.