Fighter Yukina

What if Yuki had Hiei's role?

Abandoned for being born too weak,
rough upbringing making her like canon Hiei (right down to the Jagan Eye),
Kuwabara would fall for her and be nice to her despite her rude behavior,
his admiration becomes infectious, and she gets tsundere around him, warming up to him,
etc., etc.

Her attacks are:

Dragon of the Frostbit Flame (giving her frostbite instead of burn marks)
Fist of the Frozen Flame
Fang of the Frostbit Flame (her version of "Sword of the Darkness Flame").