GoodPuffer is the protagonist of the Ocean Terror myth alongside his best friend, AngeredFish. He serves as one of the builders / engineers for the hotel facility, and is considered highly intelligent for his ability to build machinery and such.
GoodPuffer has expressed a disliking and sometimes hatred for humans. This is most likely due to what little he sees of humanity being generally bad, such as harpoons and other sea life hunting equipment. Despite this, GoodPuffer clearly cares for his friends and those around him. He is particularly protective of AngeredFish and safeguards him in dangerous situations. GoodPuffer also seems to care deeply about nature and the living environment around him.

As for his voice description, he canonically speaks in a childlike broken English, so I expect him to be wacky and whimsical, but still; he's also highly intelligent and has faced a whole lot of trauma so have fun balancing those two aspects of him