Lulala Heine is a mermaid distinguished by honey blond hair, green eyes, and warm-toned skin. Her physical traits feature vibrant yellow and black fins on her tail, webbed fingers, sharp yellow ears tipped in black, and gills along her ribs. Though equal in age to her peers, her petite frame often causes others to mistake her for younger. She typically wears an orange, yellow, and teal hooded top with a frilly skirt adorned in teal gemstones, her arms wrapped in white ribbons that end in orange frills at the wrists.

Financially responsible for her mother and at least three younger siblings, she frequently surfaces at Merrow Waterways to earn money through singing. This commitment remains unwavering even during health setbacks, such as performing while suffering gill inflammation from extended air exposure. Her background highlights independence and familial duty, contrasting with other mermaid narratives.

Personality-wise, she radiates confidence in her singing talent and displays selfless bravery. With a tomboyish attitude, she reacts fiercely to doubts about her capabilities, readily accepting perilous missions—whether rescuing a drowning boy despite impaired gills or aiding combat against foes. She visibly bristles when treated as a child, particularly by Glenn or Saphentite Neikes, asserting her maturity.

Her abilities include an enchanting singing voice used for income, natural underwater respiration, and disproportionate physical strength. She demonstrates this strength by singlehandedly towing a passenger-laden gondola against a current—a feat typically requiring a full-grown merman. In fights, she projects high-pressure water streams from her hands to incapacitate adversaries.

Key relationships involve a sisterly bond with mentor Saphentite Neikes, whose infantilizing tendencies spark friction. She holds deep respect for Skadi Dragenfelt, undertaking tasks without question and dismissing perceived dangers. Her dynamic with Glenn Litbeit begins professionally when he treats her gill inflammation; she later develops feelings but chafes at his protectiveness, occasionally bribing his sister for romantic approval.