Deuteragonist

The deuteragonist is the second most important character in a story.

examples

Finn jordan was the deuteragonist in the first season

Creeper was the deuteragonist for the first half of the second season

Greg jordan is the current deuteragonist

other examples

Sheep was the deuteragonist in the episode cow and sheep

steward was the deuteragonist in the christmas special

Kenny Grimes was The deuteragonist in the halloween special