In the story world of Carrion, drug users are the enemy. As a distinct social group they are to Reiner and the prohibitionist what the Jews were to Hitler and the Nazis, “if we did not have them we should have to invent him. It is essential to have a tangible enemy”.
They’re the outsider, the other, the enemy, the threat that people can be united against. Defeat drugs and the world will be a better place.
From Reiner’s point of view, the choice to do drugs represents a kind of desire for freedom, that poses a direct challenge to the security he craves. This makes Adam’s animosity towards drugs, more about his desire to be part of something bigger. Which raises the question, if you strip away that belonging would the animosity go with it?
Adam wants to be part of something bigger. The price to become part of that something is his sister. Unwilling to pay the piper he is exiled, forced to experience the world thusly.
Does that make Adam’s animosity to drugs environmental, a learned behaviour that has more to do with his relationship with Christine, than some innate hatred of drugs and users.