I need help...protecting my sister

Ive been through this with two sisters.

Theres really nothing you can do. She's not going to listen to you UNTIL something bad happens.

I know you want to try and stop that from happening but unless you have very special relationship with her ( which you dont or she would have already listened to you ) your words will fall on deaf ears.

My lil sister moved out to LA ( where I live) at 19 to be a 'model'.. well within 6 months she was a stripper, on drugs and hanging out with a very bad crowd ( who she was screwing was the least of my concerns at this point ).

She ignored me ( even though shes always looked up to me) UNTIL she woke up one day in a strange house she didnt recognize with a bunch of guys she didnt know and all her money was gone from her purse. She still doesnt know what happened but that incident led her to talk to me and I had her move in with me and I took care of her while she kicked the drugs and stopped stripping.

You sound like a great brother..just be there when she falls.