Another mermaids are good and different, another mermaid are evil queen Nerissa. Sienna luna were lost their family died by evil mermaids queen Nerissa, but Agatha and her mother look a different mermaid, they were keep her safe and her daughter Ruby Gillman They were close their friend sienna and ruby, and her brother Sam Gillman She want stop queen Nerissa to save the ocean and other people, and the Gillman's family.