Redtailgal,
When I was a child in an alcoholic home I wanted someone to rescue us. No one ever came for me but what you are doing for that child is incredible. If only we could rescue them all somehow.
I just checked and NC is a one person state and you can legally record conversations with your brother without his knowledge and consent. A trip to an electronics store will give a lot of great devices for this purpose that are inexpensive. Start documenting and archiving every jot and tittle.
Do visit as many attorneys as you can... they usually will give you a free consult visit. Lawyers are not created equal and with the opinions and advice you get from them you can get a solid plan for the future.
Alanon will be a lifesaver for you... it was for me. A support network that understands the devastation of loving someone who is destroying themself and even turns into a monster you don't know is psychologically damaging. How can it not be?
Lastly, kids of untreated alcoholics can benefit from a counselor who understands addiction and specializes in kids. I know my kids did when I divorced their addict father and they are pretty normal, happy non codie non alcoholic/addict successful adults.
I didn't know about alateen but it can also be helpful.
Having an alcoholic parent that is emotionally unavailable is scarring. Again, thank you for your sacrifice of your time, money and your life to this poor child who has a lot of road ahead of them with that man for a father.