As McConaughey sees it, these are the "Four Stages of Rustin Cohle":
"Back to being a part of the body. He's coming off of years being Crash. He's trying to walk the line. Monk-like. Trying to hold it together. And that's a lot easier with less interaction with others. There's a mechanical side to him. He needs the regimen of the homicide detective. He needs the case to actually survive. One, because he's great at it. And two, because it's going to keep him from killing himself."
"He's our deep, narco wild-ass. A guy who goes all the way. This is where Cohle has all the freedom. He can go over the edge as this guy. And inside, he loves the life of Crash even more, because the shackles are off of him. He knows he may die sooner living this life, but there's a freedom and peace in that knowledge for him."
"A little looser mix of Crash and the '95 Cohle. A guy who's made his boundaries clear and has to mark less territory, so he's relaxed into his way in the world. But the case is still his lifeline. He has some small hope that there's going to be a way out of his being and pain and criticism, so he makes an effort into domesticity, a la the girlfriend. Only to prove that he was not made for it, and there is no way out. So what does he do? He resigns to his nature, once again."
"This guy lived longer than he hoped. Fallen prey to his own beliefs. More cynical, angrier, he's had to endure the existence of this shitstorm called life. A little ragged, more rough edges, living in a place where he can manage himself. Not too close. He's not in the CID. But he's not in Alaska. He's a guy who's resigned to his indentured servitude of being alive. But he despises the sentence and the penance. He will not accept defeat. He's not going become a madman, he's not going to kill himself. He wrestles the devil every day, and he realizes that this may last a lot longer than he ever hoped for."