Breaking of impalas

This is the story of Ryan. She lost her parents to hell hounds when she was 2, when her parents made a deal with a crossroads demon to let her never die from the supernatural. Which meant Death himself had to take a part in this girl as well, Death had a thought about this girl. If he just let her be immortal he wouldn't have to worry about her, but he decided to adopt her instead. With her immortality her aging process stops at the age of 23. She soon meets the Winchester bros and goes on her long car ride.