Hedwig functions as the primary antagonist throughout all official media. Originally a sorceress, she shared a romantic past with Anselm in their youth. Anselm ultimately banished her to the sea as her pursuit of power grew uncontrollable, establishing the core conflict that drives her actions. Following this banishment, she exists as a sea witch possessing a mermaid-like form distinguished by a moray eel tail rather than a conventional fish tail. Her physical appearance often features long fingernails capable of releasing prehensile vines, a frequently employed offensive ability.

Her central objective focuses on obtaining the Amulet of Power, which she believes will grant her dominion over both land and sea. To achieve this goal, she repeatedly devises schemes to capture Marina and Prince Justin, intending to exchange them for the artifact. She commands a group of loyal minions to execute these plans. Dudley, a dim-witted scalloped hammerhead shark, serves as her prominent second-in-command and primary source of comic relief. Ray (or Manta), a giant oceanic manta ray, functions as her transportation and spy. Hugo, a giant Pacific octopus, acts as her physical enforcer. She also maintains an army composed of barracudas and tiger sharks.

Her magical abilities extend beyond her signature vine attack. She demonstrates proficiency in brewing potent potions, including the Potion of Change, which temporarily transforms Marina into a human or grants Justin the ability to breathe underwater. She also employs enchanted objects, such as a hypnotic flute capable of placing characters under her control. Her knowledge encompasses magical artifacts like the Golden Tablet, which possesses the power to permanently make Marina human.

Specific events drive her character development. A notable instance involves her consuming a Potion of Reverse, which unexpectedly renders her benevolent. This temporary state proves preferable to her minions and others accustomed to her malevolence. Her ultimate fate concludes with a permanent transformation. Defeated with the assistance of allies including King Nestor and a dragon named Skipper, she is irrevocably changed into a sea dragon, specifically a leafy sea dragon, forcing her to adapt to an entirely new existence. Her personality consistently reflects ambition, vengefulness towards Anselm, and ruthless determination to seize power, regardless of collateral damage.