While she was a standout character in the second movie The Hunger Games: Mockingjay duology wasted Jena Malone's Johanna. The Hunger Games franchise is based on the book series by Suzanne Collins, which finds lead character Katniss forced to take part in a death sport in a dystopian future. She later finds herself very reluctantly at the head of a rebellion, and the huge success of the first Hunger Games movie not only made Jennifer Lawrence a movie star, but it also led to a tidal wave of other YA sci-fi films.
Movies like The Giver, The 5th Wave, and The Divergent Series piled into cinemas, and while some were solid hits, the target audience soon became bored with the oversaturation. This period also led to a mild backlash against the trend of taking the final book in a series and splitting it in two to maximize profits. This worked for Harry Potter and the Deathly Hallows – Part 2, but famously backfired in the case of The Divergent Series: Allegiant, which wasn't successful enough to support making the planned final part. Even The Hunger Games: Mockingjay - Part 2 reported disappointing returns, though it still made a comfortable profit.
In The Hunger Games novels, Johanna Mason is the survivor of the games from District 7 and became a fan favorite for her fearless attitude, spikey dialogue and handiness with an ax. Jena Malone played the role in The Hunger Games: Catching Fire, and while Johanna didn't get a ton of screentime, Malone stole just about every scene. Sadly, despite a warm reception from audiences, Malone wasn't given much to work with for The Hunger Games: Mockingjay - Parts 1 and 2.
Since The Hunger Games: Mockingjay - Part 1 splits the book in two, the absence of Johanna makes sense, as she and Peeta have been captured by the Capitol and are being brutally tortured. They're both rescued in the finale, with Peeta being brainwashed into an attempt on Katniss' life while Johanna is discovered bald, emaciated and covered in bruises. In the books, it was revealed she was tortured with water, being doused and shocked endlessly. This would lead to her developing such a fear of water that she rarely bathes.
Unfortunately, The Hunger Games: Mockingjay - Part 2 cuts a lot of Johanna's character development from the book for speed. Gone is her training to be a soldier alongside Katniss - before failing a final stress test - and instead, she only appears in a few scenes. Jena Malone is still great and brings a welcome, barbed humor to the movie, but her presence is missed during Katniss' raid on the Capitol. Again, this makes sense since she just endured inhuman torture and wouldn't be in fighting shape, but the result is one of the franchise's most well-liked characters is left with very little to do in the finale.