Have Hart, or you will loose your mind

Issy is a normal girl, a huge fan of supernatural and all alone. She's soon faced with a choice, help an angel and get a chance of bringing her sister back? Or stay home, in her universe, where it's safe and normal. Obviously- Who wouldn't say yes to the chance of meeting the Winchesters? But she isn't an idiot. She's not just going to let someone possess her without consideration