I've been thinking about this fanfic idea for a while... This is Nagisa!

She is a young, female wolf from an unknown origin. She was captured by Darcia the First and brainwashed into assisting him, being the original key to paradise. This trance was eventually broken upon coming to contact with a hanabito, who awakened her true identity.

She betrayed Darcia after falling in love with another, very familiar-looking, wolf named Haiki, who came to prevent the early opening of paradise. They say she lead to everyone's demise.