The functioning drunk part reminds me of a roommate I had in college. He was popped for a DUI, while passed out in the passenger seat of a running car on a cold night. The police did not blood test him for over 24 hours. He was incarcerated the whole time... and still tested over the legal limit.
I have no Idea how he survived being that drunk.
But for the year I lived in that house he was "living the 12 steps." But it turned out, when he went to his room at night he would drink a 12 pack of room temperature beer. I have do not know why he thought it was important to live the sober lie, around two other roommates that did drink socially.