Oc is a demon, but not by choice

Basically, she was sold when she was really young to a crossroads demon that went rogue.

She never had a real family. Her mother was the one who sold her to a desperate human who sold her to a demon.

She never died, she was taken to hell. She slowly aged over hundreds of hell years, which ended up only being a little over a decade in earth years.

She never tortured anyone. She stayed strong and eventually got used to the pain she received, so much so that she became a demon (sort of).

She isn't a full demon. She can only heal people, and her eyes don't even turn black ( because she is in her own body). However, she appears as a demon to beings that can see them.

She still has a soul, but the demon part of her covers it up.

When her demon captor doesn't return for years, she eventually breaks her chains and roams hell in search of a way out. On the way, she "meets" Crowley, who surprisingly doesn't care and lets her be.

She finds a library in hell with books upon books. She ends up staying and reading all of them, learning many languages, as well as things about creatures on Earth and much more information than she needed to know.

When she finds the door out of hell, she roams Earth, eventually finding a job in Lebanon, Kansas.

She unfortunately finds that she can't age. So, she spends her time learning and reading, all in order to protect humanity against anything, including humans.

She becomes a junior firefighter, and she aims to study to be an EMT/ Paramedic.

And of course, she's a hunter.

So, Sam and Dean kidnap her after Castile spots a demon in Lebanon. She tells them some of her story, but they don't believe a lot of it.

They end up trusting her enough to let her be, but they force her to stay with them in the bunker so they can keep an eye on her.

Takes place maybe starting around season 9, but doesn't really follow the plot of episodes except for certain events.

Ok, So I have a lot of ideas for this, and I might end up just writing this fanfic. I have a ton more ideas with this, and I really wanna take it further but I never have the time. However, if you want to use this plot you can :)