Charlie is a friendly humble slime, and enjoys making new friends. He is bubbly and kind-natured, incapable of hurting a fly, unless a friend is hurt, and those are the only times he is willing to cause pain. He has taken an unusual liking to his duck friend Quackity, and has gained a little bit of an obsession for him. He is quite unknowledgeable of human emotion, and is quite the curious one, always asking what it's like to be human. He refers to people as their name and where they're from.