Posy Hawthorne is the youngest child and the only female child in the Hawthorne family. She grew up in District 12 and has three older brothers: Vick Hawthorne, Rory Hawthorne, and Gale Hawthorne. Posy's mother, Hazelle Hawthorne, took care of her and her brothers.
Around the time Gale was whipped for illegal poaching and had to be taken care of by Mrs. Everdeen, Posy became ill with measles and was nursed back to health by her mother. Mrs. Everdeen also sent medicine for Posy to recover.
In the 75th Hunger Games, Katniss Everdeen was able to hear jabberjays mimicking Posy's cries in one section of the arena. This contributed to her giving up trying to hunt the birds and instead curling up in a ball, trying to block out the noise.
Posy found refuge in District 13 after the bombing of District 12, along with the rest of her family. At one meal, Posy asked if Octavia, a member of Katniss' prep team, was sick because the pallor of her skin was a light shade of green. At first Octavia seemed saddened about it, but then Posy said Octavia would look pretty no matter what shade of color her skin was. This gave Octavia a fondness for little Posy.
Posy lived with her mother, Hazelle Hawthorne, and her three brothers; Rory, Vick, and Gale. She never met her father, as he died just before she was born in the same explosion that killed the father of Katniss Everdeen. Katniss Everdeen and her family are very much like family to them, due to her close relationship with Gale. During the 74th Hunger Games, the Hawthornes were publicly referred to as Katniss' cousins, to keep them safe from her and Gale's friendship.
- Katniss heard Posy's voice, along with those of her siblings when the jabberjays mimicked the voices of loved ones being tortured in the Quarter Quell. Thus it could be inferred that she was important to Katniss as part of Gale's family and her "cousins", Katniss described her as " Posy, helpless little Posy".
- She is one of the youngest characters mentioned by age in the series.
- In The Hunger Games film, Katniss Everdeen says to Gale at the beginning of the movie that they couldn't live out in the woods because she has Primrose Everdeen and Gale has his brothers to look after, though she does not mention his younger sister, Posy.
- Posy's favorite color is said to be bright pink, which was revealed when Gale teased her and told Octavia that Posy would like her even more if she were bright pink.