Johanna is a survivor from the Quarter Quell. At first, the rebels could not rescue her. She was with Peeta and Annie being tortured by the Capitol. The Capitol had soaked her and then used electrical shocks to torment her during the imprisonment. She was eventually rescued from the horrifying treatments.
When she is taken to District 13, she developed a fear of water. She wanted to join Katniss in the fight, but her damage was too much. Johanna also becomes addicted to morphling. Once she overcame her addiction, she still could not tolerate being near water.
Just as the other victors of the Games, Johanna came to District 13 to learn she lost everyone she loved. A deep sadness went through her when she left District 13 empty handed. She realized there was nothing to call her own.
At the end of the book, Johanna voted for another Hunger Games. She did so because the thought of punishing the citizens of the Capitol and the granddaughter of Snow. She felt there was a justice that needed to be satisfied. The answer to it would be to force the relatives of the people who forced her.