Chopper was one of the three predators to enter the underground arctic pyramid in Alien versus Predator. He also stuck close to Celtic, one of his brothers. He was the first Predator killed on-screen by a Xenomorph.
In the Movie
Along with Scar and Celtic, Chopper menaces the humans setting up camp near the Pyramid. He mostly follows Celtics lead, suggesting the larger predator is the older and more dominant of the two. While Scar goes off on his own, Chopper and Celtic aim to retrieve their stolen Plasma Casters. They get into it with the group of humans directly, killing several of them. Chopper, in particular, goes after Alexa Woods, who was planning to attack Celtic with an ice pick. He interrupts this by kicking her hard into a wall.
Chopper looms over her, preparing to kill her with his arm blades, but fails to notice the Xenomorph behind him. Grid impales him through the back, then kills him with a headbite, discarding his body and preparing the battle the enraged Celtic predator.
Chopper's face is never seen, however he is distinct from his brothers by way of his arm blades. The crown of his mask has dipping grooves in its surface and he himself has tiny skulls stuck to poles on his armor.
Not much can be gleaned about Chopper's personality.