The title may be confusing, let me elaborate:

There's me, and my friend, both early 20-ish. He has a cousin (16-17 fuck if I know exactly) that is just godawful. She talks back, and is incredibly rude, to everyone, keeps spending money she doesn't have on shit she doesn't need (as you may have guessed she has no father, left her and her mother a few years back, and her mother's got health issues and can't really work properly). Keeps doing stupid shit to attract attention to herself. She stole her mother's fucking car and drove, but she has no idea how to drive and could have crashed somewhere. They (her and her mother) were getting kicked out of the apartment and my friend's dad offered to take them in for however long they need, she made a fuss that she doesn't want that cause she "won't be able to make parties". Keeps getting into cat fights with random chicks...etc...etc...

The tl;dr is that she's a spoiled fucking brat that keeps doing dangerous shit and I'd like to "fix" her, however much is possible, because clearly she has no father figure in life. No stupid ideas that I will be creating a kind and polite unicorn that's NAWALT, that ship has sailed a long time ago lmao. Just to calm her down a bit before she fucking hurts herself, or someone else in the process.

I am not looking to date/fuck her (as she is fucking 16 and my friend's cousin), so why am I posting this here? Because I figure with a couple of modifications the TRP principles could be applied in this situation, with a hopefully good result.