After landing on a Fireplace, Hoppers will become Flaming Hoppers.
Flaming Hoppers behave similarly to normal Hoppers in that they will randomly hop around the room, following Isaac only when within a certain range. Unlike normal Hoppers, Flaming Hoppers will follow Isaac within a much larger and more aggressive range and also gain tripled HP, a doubled jumping distance, and a faster movement speed. Putting out all Fireplaces in an area with Hoppers is a recommended strategy to stop them from turning into Flaming Hoppers.
Eternal Champion Behavior
Eternal Flaming Hoppers take longer to start hopping, but will directly chase Isaac with every hop and fire tears in the cardinal directions on every landing.