Prior to his appearance in Mockingjay, Pollux was turned into an Avox by the Capitol. It is assumed that the reason behind him joining the rebels in District 13 is for revenge.
As an Avox, Pollux worked in the utility pipes and the Transfer under the Capitol; he was thus very knowledgeable about the passageways and was able to help Katniss and the rest of Squad 451 in maneuvering underground to President Snow's mansion. His brother, Castor, eventually bought Pollux's way above ground after five long years.
At some point after working underground, he began to work as a cameraman. As he begins to work for Katniss, she defines him and his brother as looking like insects because of the heavy mobile cameras which usually encase their bodies.
When Katniss and her filming group were in the meadow around District 12, Katniss sits next to Pollux during a break. They start whistling tunes and birdcalls to mockingjays and wait for their return whistles. Pollux then writes the word "SING?" in the dirt, asking Katniss to sing. In the movie, he instead taps his lips and points to Katniss, prompting that she sing. She sings the song "The Hanging Tree" for him, which makes him very emotional.
In the movie, Pollux also comes to District 8, where he films Katniss's speech to the rebels and Snow. He's once again present when Beetee is hacking the Capitol's safety system, filming Finnick's distraction speech.
While in the Capitol, Pollux helps guide the group underground and toward the mansion, but gets lost in a crowd of Capitol citizens with Cressida. After the war is over, he and Cressida are sent out into the districts to cover the wreckage of the war. His brother Castor, however, was killed by lizard muttations in the underground passageways, much to Pollux's grief.
As the only surviving member of Cressida's team, Pollux joined her again in the postwar period, filming war damage in the other districts
Pollux is described as a burly man with sandy hair, a red beard, and deep blue eyes. He resembles his brother, Castor. He has no tongue, as it was cut off when he became an Avox.
- Castor and Pollux owe their names to twin brothers in Greek and Roman mythology. The myth states they had the same mother, Leda, but different fathers (Tyndareus and Zeus, respectively). This technically made Castor mortal and Pollux immortal. Strangely, Pollux lives, and in the legend Pollux is immortal (lives forever), whilst Castor dies in the books, the legend Castor is mortal (can die).
- In the scene where Katniss first meets Pollux and the rest of the crew, he can be seen signing "HER BEAUTIFUL THINK" (The translation has been debated from "I think she's beautiful." to asking Castor if "(he) thinks she's beautiful") Castor responds by simply signing "yes".