Mertle is an incredibly spoiled little girl. She is the leader of a clique of girls, who follow her every command. She has a strong disliking towards Lilo and refers to her as "Weirdlo" for most of the franchise. It's shown in the TV series that her "friends" aren't too fond of Mertle's mean and bossy attitude, implying that, despite the fact they hang out with her, they don't actually like her. Mertle takes great pleasure in putting down, insulting, bullying and making fun of Lilo.