Katniss believed that Johanna was only in the alliance for Finnick, when in reality, she was only protecting the Mockingjay so as not to end the rebellion early.
Johanna and Katniss take the first watch that night. Johanna tells her that Mags was Finnick's mentor and half of his family. She also tells her that she was with Wiress and Beetee because of Katniss. According to Johanna, Haymitch said if she wanted to ally with Katniss, she'd have to have Wiress and Beetee with her.
At this point, Johanna knocked Katniss over the head with the heavy metal cylinder, then cut the tracker out of Katniss's arm so the Capitol would be unable to find her. Johanna also smeared blood across Katniss's face to make Enobaria and Brutus believe she was already dying. Johanna then led the Careers away.
In the case of Johanna, they each hated each other because that was what the Capitol had taught them to do. They were from competing Districts, and the idea of the Games was to keep the lesser citizens of Panem distrustful of one another and unwilling to form alliances (or raise arms in war).
Up until almost the end of the book, Katniss is mad that Johanna betrayed her and tried to kill her in the arena. She sees it like this: Johanna knocked her out, cut her up, and left her for dead. It's not until the very end that Katniss finds out that Johanna was working to save her life.
The Life of Johanna Mason (Hunger Games Explained)
Why does Johanna hit Katniss over the head?
Katniss Everdeen
Even though the two were now allies, they still didn't trust each other. During the escape from the arena at the end of these Hunger Games, Johanna 'attacked' Katniss for the purpose of removing a tracking device from her arm, then lead Brutus and Enobaria, the District 2 tributes, away from Katniss.
Johanna Mason was the axe wielding victor of the 71st Hunger Games from District 7. Snow would later orchestrate the slaughter of her entire family as punishment for her defiant nature.
The female Morphling, however, appears almost coincidentally, and Peeta even mentions that they don't know her real name. Given that she is willing to make the ultimate sacrifice to protect Peeta, it's safe to assume that the Morphling was committed to the rebel cause.
Ever since their first meeting in the elevator, Johanna Mason has had her eye on Peeta. Even though she came off as cold and distant, she was never afraid to show her admiration for Peeta. In that same scene in The Hunger Games: Catching Fire, Johanna asked Peeta how he felt now that everyone wanted to sleep with him.
The following year after Lucy Gray Baird's victory, another female tribute emerged as the Hunger Games winner. Mags Flanagan became the first victor from District 4, living off of nuts and her survival skills by creating fishhooks. She was also the first victor to move to Victor's Village before serving as a mentor.
Unable to find Peeta and hearing a cannon, Katniss nearly attacks Finnick, suspecting his betrayal, but he reminds her to "remember who the real enemy is." Katniss attaches the wire to an arrow, firing it into the arena's roof just as lightning strikes.
Johanna clarifies, stating that Peeta has turned into his evil mutt identity given the way he verbally attacks Finnick and Katniss. Gale even sees a bit of himself in how Peeta acts and speaks.
This suggests that Katniss loves Peeta, and not just because she feels that she owes him her life. Instead, Katniss wants to protect him and bring him home because she has strong feelings for him, even though she isn't sure what those feelings mean.
Peeta used the dyes to paint a picture of Rue after Katniss covered her with flowers when she died. He says he wants to hold them accountable for killing Rue, and Effie tells him that that kind of thinking is forbidden. Katniss then tells the team she hung a dummy of Seneca Crane.
Their relationship was all friends. They trusted each other, but that doesn't mean they had romantic feelings for each other. Plus, Cinna's too old for Katniss.
Katniss made the choice to build her future with Peeta. If she didn't love him, she wouldn't have made that choice. Katniss made her whole world about getting the people she cared about to the next day, her choice to survive with Peeta proves her love for him.
Later, the two learn President Snow considered their actions to be an act of rebellion against the Capitol. After their last interview, in which the two continue to affect their romantic feelings for one another, Peeta comes to the realization Katniss has staged her love for him all along.
Yes, Katniss did develop an addiction to the morphling, on account of constantly being sedated with it, however, I wouldn't say that she was an addict. An addict is someone who goes to a substance (or whatever their 'poison' may be) under their own mind.
Chia Mags kisses Finnick on the mouth to briefly let him know that this is the last time she will see him. It's her way of saying "Goodbye" but in a more affectionate way.
Johanna Mason developed an addiction to morphling while hospitalized in District 13 for the torture she endured in the Capitol. When she was weaned off, she instead dipped into Katniss's supply.
Haymitch Abernathy, the mentor for Katniss and Peeta in The Hunger Games, won his own Hunger Games through smart tactics and outsmarting his opponents. Winning the Hunger Games came at a great cost for Haymitch, as President Snow ordered the death of his family and girlfriend as punishment for his rebellion.
Johanna pretended to kill Katniss and dug out her tracker. She then led Brutus and Enobaria away from Katniss and they followed Johanna. Johanna was captured by the Capitol but was rescued by District 13.
