This scrappy fuzzball from The Hunger Games trilogy by Suzanne Collins belongs to heroine Katniss Everdeen’ sister Prim. He appears in all three novels (and four films) as a comforting companion to Prim and an annoyance to Katniss, with whom he’s not on the friendliest of terms due to her (expositional) attempt to drown him in a bucket—bad Katniss! Eventually, though, she accepts Prim’s attachment to him.
Buttercup is said to be a good mouser and even catches the occasional rat. He’s described in the novels as looking a little worse-for-wear with a mashed-in nose and half of one ear missing—which tracks, considering his rough life in the impoverished District 12. His name comes from Prim insisting that his muddy yellow coat matches the bright buttercup flower.
In fact, the makers of the Hunger Games films tried to pull a fast one by casting a black-and-white cat as Buttercup in the first movie. Collins and fans (rightfully) demanded he be changed to a yellow-haired cat for the rest of the films to stay true to the novels and his namesake.
When the Everdeen family moves into a new, much larger house in Catching Fire, Buttercup and Katniss slowly bond over their shared dislike of their new home. Katniss even starts sharing scraps from her hunting kills with him and deigns to give him the occasional behind-the-ear rub.
In Mockingjay, when the resistance moves into what’s essentially a massive underground bunker in District 13, Katniss finds Buttercup while on a venture to the now-destroyed District 12 and brings him back for her sister, even though pets aren’t allowed.
At one point when 13 is on lockdown during a bombing from the Capitol, Buttercup helps ease the tension by entertaining the troops, so to speak, chasing a flashlight beam and giving Katniss an epiphany about how her enemy is taunting her. And making everyone LOL. (Even in wartime, people can still laugh at cat antics—call it a testament to the human spirit.)
We don’t get to see a ton of Buttercup, since he lives in District 12 (and eventually 13) and our POV character Katniss is usually off fighting for her life somewhere else, but he makes his few appearances count.
Case in point: this passage from Mockingjay, which I’ll let close. Now that I’ve typed it out, I need to go find whoever’s chopping onions around here…
My head snaps around at the hiss, but it takes awhile to believe he’s real. How could he have gotten here? I take in the claw marks from some wild animal, the back paw he holds slightly above the ground, the prominent bones in his face. He’s come on foot, then, all the way from 13. Maybe they kicked him out, or maybe he couldn’t stand it there without her, so he came looking.
“It was a waste of a trip. She’s not here,” I tell him. Buttercup hisses again. “She’s not here. You can hiss all you want. You won’t find Prim.” At her name, he perks up. Raises his flattened ears. Begins to meow hopefully. “Get out!” He dodges the pillow I throw at him. “Go away! There’s nothing left for you here!” I start to shake, furious with him. “She’s never ever coming back here again!” Out of nowhere, the tears begin to pour down my cheeks. I clutch my middle to dull the pain. “She’s dead, you stupid cat. She’s dead.” A new sound, part crying, part singing, comes out of my body, giving new voice to my despair. Buttercup begins to wail as well. No matter what I do, he won’t go. He circles me, just out of reach, as wave after wave of sobs racks my body, until eventually I fall unconscious.
But he must understand. Because hours later, when I come to in my bed, he’s there in the moonlight. Crouched beside me, yellow eyes alert, guarding me from the night.—Suzanne Collins, Mockingjay