Katarr was always meant to be the opposite of Rinne; the embodiment of all Rinne is fighting against. Where Rinne was brought up with the warmth and comfort of friends, Katarr was abducted, neglected, and taught to seek solace in pain: it was life’s true constant.
Rinne will stand against Katarr for the belief that such an evil does not belong in the galaxy, where Katarr will fight tooth-and-nail to prove that she is Rinne’s better; that all her life, her instructors were wrong: that she was not weak. She would never again kneel before anyone. She would surpass Rinne, no matter the cost.