In the Games he seemed to be a Ruthless killer, He killed mostly a lot of people in the Games, Including having the 2nd kill in the Bloodbath
In the Bloodbath Calix managed to get 3 people although on of them was Dereck Mage people don't know who the others was. They heard him talking about it while watching the games. They think it's the District 12 female and the District 9 male, After the Cornucopia he and the Career's gatherd up there belongings and left the scene hunting for people. Once they got about 3 people including Jason from District 7, They went to sleep.
On Day 2 they got awakened by a Cannon and howling. They thought it was mutts although people thought it was Calix this was clarified as President snow should the fotage of the mutts attacking the District 5 female later on they killed the District 3 male. After that they weren't really mentioned anymore
Day 3, Was when Calix dies. Although it's not mentioned we know that he died between Day 3-4 since Reginna woke up from Day 3 to find Deema dead. After his death it seemed like Grace The District 4 female went crazy.