Miss Fox Demon Always Likes to Tease Me

What will you do when an uninvited guest comes to your home and claims to be a fox fairy who has lived for five thousand years? The purpose of coming to you is to resolve karma and become a fairy? That would of course prevent her from becoming an immortal. I understand the truth, but why is this fox fairy lady so good at flirting despite being an old fox demon who has lived for more than five thousand years?