Instructions
Walk along the ledges and ventricles until you find the room with the character essences.
Dodge the character essences. They are fast-moving. Try to stay on ledges and out of their reach.
Look for the bloticles along the ventricles. They are bright green splotches and easily recognizable.
Paint the bloticles until they pop. Try to paint them from a distance with a long stream of paint instead of a short burst to avoid the character essences. The character essences will vanish when the bloticles are all painted and popped.