This is the article I just read:

http://gettingpastyourpast.wordpress.com/2010/08/05/being-the-identified-patient/

Here are a few other resources that describe ACOA and family roles:

http://alcoholselfhelpnews.wordpress.com/2007/12/16/what-is-acoa-co-dependency/

http://www.counselingcenter.illinois.edu/?page_id=144

http://www.associatedcontent.com/article/73103/the_family_secret_adult_children_of.html?cat=72

While you may identify with one "main" role, there is some overlap.

I was mostly the Hero, my sister was the scapegoat.