Onyx

Onyx is what happens when a merman survives where almost nothing else does. Unlike shallow-water merfolk, whose bodies evolved in sunlit reefs and temperate coastal waters, Onyx comes from the deepest parts of the ocean. He is enormous. His tail alone stretches well over eight feet, perhaps considerably longer when fully extended. It is covered in overlapping black scales that appear almost matte in darkness but reveal subtle bronze-gold and oil-slick colors when exposed to sunlight. Along the ridges of his tail are hard, finlike structures that can flatten against his body when he swims or flare outward when he’s threatened. His enormous fluke is asymmetrical in appearance, jagged and heavily ridged rather than delicate. It resembles something designed for propulsion and survival rather than beauty. His upper body is deceptively human. Pale skin. Lean muscle. Broad shoulders. A narrow waist. Long arms ending in unusually long fingers tipped with dark, retractable claws. His arms possess elongated fins running from his forearms toward his elbows, usually lying flat against his skin but spreading dramatically when he swims. His face is the one thing that seems almost completely untouched by his monstrous adaptations. It is long, narrow, and sharply handsome, with hollow cheeks, a straight nose, high cheekbones, and a pointed chin without a cleft. His black hair falls around his face in wet, uneven layers. And his eyes are completely black. No visible iris. No discernible pupil. Just glossy, bottomless black. His gills lie along the sides of his neck in several delicate slits, opening and closing almost imperceptibly when he’s submerged. He has excellent vision in darkness, but sight isn’t his primary sense. Sound is. Onyx can map an entire cavern through echolocation. He can detect movement beneath sand. He can distinguish the heartbeat of different animals. He can tell when something is approaching before it comes into sight. And eventually... He learns to recognize your heartbeat.

Updated September 23, 2026