Rayon
Ron meets Rayon and initially has a hatred towards her. They soon after start a business together, The Dallas Buyers Club, to help AIDS patients find drugs that can actually help them. This relationship is a symbol of breaking down stereotypes and unfounded prejudice through helping other people to heal.
FDA
The FDA plays a major role in Ron and Rayon's ability to take and sell drugs that help AIDS patients. The FDA is a symbol of regulation necessary to protect people from unproven drugs while simultaneously being an oversight committee that allows for corruption to occur through drug companies gaining profits off the deaths of human beings with experimental drugs. However, there are already drugs available that work to prolong the life of AIDS patients.
Dr. Saks
Dr. Saks treats Ron and Rayon at the hospital in Dallas. She initially believes in the trial and eventually realizes it is unjust. She is a symbol of practitioners/doctors having the ability to put an end to trials they know won't work and that they are not beholden to maintain loyalty to the system for the sake of the system, but rather they serve the well-being of the people.
Mexico
Dr. Vass has had to leave the United States because he's had his medical license revoked. He now practices in Mexico where he helps Ron to find a cocktail of drugs that prolongs his life 7 years. Dr. Vass is a symbol of a person who is willing to do whatever it takes to heal his patients, for better or worse. That his reputation and money are of less value to him than the truth.
Resign
Dr. Saks is asked to resign by the hospital's board. She tells them they will have to fire her. This is a symbol of her Taking a stand against the hospital which will have to take some form of responsibility in their actions and won't be able to simply blame a resigned physician for their actions moving forward.