Gingerly Crossing Fine, Fragile Lines

Merfolk were what humans would call "psychics."

They were telepaths able to read and communicate with each other and other creatures using their minds while underwater. They were empaths who easily accessed memories, sensations, and perspectives that weren't their own.

It revealed any disdain, disappointment, or disgust anyone held behind pleasant smiles and welcoming demeanors. This prevented rampant delinquencies in merfolk communities, allowing them to become a cohesive, united and peaceful civilization.

Their psychic abilities coupled with their ability to wield magic made them formidable guardians of the ocean. They accompanied sirens in bloody campaigns against threats, shattering their opponents' psyche with their minds. This was the true nature of the merfolk song. Humans who experienced it sensed the tendrils of merfolk mind control as enthralling songs and unbreakable illusions. Their ships would be devoured by the ocean before they could realize what was happening.