I like her lore, but it doesn't match her ingame character.
Her lore states that she is a practitioner of dark magic, who commands a mighty shadow bear. It makes no mention of fire.
Even her title, the dark child. What kind of title of that for a champion who specializes in lighting enemies on fire?
She's the dark child so she lights you up! 
Dark magic ranges across a huge spectrum of abilities. I think it safe to assume that she specializes in fire magic, which we can now assume is dark magic because we know she is a practitioner of dark magic. Along with that we know that she forced a bear of pure evil into a teddy bear because she feels lonely. I don't know how Rito could incorporate that special ability into the game so I think they left it in the lore to show that she can do more than fire.
