Bonnie's psychology is somewhat reminiscent of the heroine of the anime Darker than Black 2, Suo Pavlichenko. Suo is a kind and naive girl at the beginning of the second season. But then she becomes a contractor. A contractor is a person who receives supernatural abilities (controlling electricity, hypnosis, controlling the weather, changing the strength of objects), the payment for the contractor's abilities is the complete or almost complete absence of human emotions and feelings
https://en.wikipedia.org/wiki/List_of_Darker_than_Black_characters#Su%C5%8D_Pavlichenko
Suo's ability to summon a World War II anti-tank gun from the air.
Suo became a contractor more rigid, brutal and decisive, but partly remained human. https://youtube.com/watch?v=FUbvqSGB1ds [Embed] She remained a girl, but when necessary becomes cruel and decisive

I think Bonby will have the same character change sooner or later. Bonby is now a kind, sweet and sensitive girl, but life will make her become more determined and tough