Nyx is a broad-shouldered tiefling with deep wine-red skin, swept-back black horns, and a long tail that moves with deliberate precision. His lower canines are slightly oversized, visible whenever he eats or gives a humorless grin. He keeps his beard and black hair carefully trimmed despite the rough life of a sailor, and maintains his horns with oil until they shine. He wears weathered scale mail over dark sea clothes, with a great axe secured across his back and two handaxes at his belt.

Nyx is controlled, observant, and relentlessly practical. He rarely wastes words, but he listens closely to orders, notices who follows them, and remembers every broken promise. Beneath his stern discipline is a protective streak reserved for people who work hard and keep faith with their companions. He is more comfortable in a storm than at a feast, and he regards unnecessary luxury as a challenge to his self-control.

Nyx was born in a storm-battered port where tieflings were treated as omens until they proved useful. His mother worked as a ship's cook, and his infernal blood made him an easy target for superstition. Nyx answered suspicion with discipline. He learned the ship's rules, memorized the order of every command, and became the deckhand who could be trusted to hold a line when everyone else was shouting. The sea did not make him gentle, but it taught him that survival depended on knowing exactly who was responsible for what.