Franz and his older sister Kate.
They kinda went their separate ways for most of his life after school.

these are old sketches of his other two sisters
His younger sister Kim:


...and Lucy (their second eldest sister)



PS
I named these characters in 1st year high school and they've served to name these people well enough. None of them(save Franz) are patterned nor named after real people.

(though it does take from the fact that the main character Franz was based on my friend named Franz and that he has three sisters).