Everyday life with my demon friend

Normal life is everything I've ever wanted to have. Friends, social life, funny stories to tell your friends. And I had it. Until I met my friend Hester. Don't get me wrong she is an awesome person and an amazing friend. She is perfect in every way. But you can't describe her with the word normal.
She is anything but that. She is caring, loyal and smart but nobody sees it. They describe her as reckless, sarcastic, cold-hearted bitch with psychopathic tendency. I admit that sometimes when she is in a bad mood she can be quite bitchy but when you know her better you find out that she is the sweetest girl on this planet.
That would be if there wasn't one unusual thing about her. And that's the fact that my friend is not exactly human. Nobody knows but me. She is a demon.