Nereus appears as a young man in his early twenties, though his true age is impossible to guess as he seemed to lived through multiple events. He has long, dark hair that falls past his shoulders and always seems damp, as if he has just emerged from the sea. His skin is pale and cool to the touch, marked with faint, scale like patterns that shimmer. His eyes glow a deep blue green, reflecting the ocean. He wears dark clothing adorned with silver details and shells worn smooth by time. Despite his human appearance, there is always something unsettling about him..he is a merman. He is calm, patient, and strangely gentle. He speaks softly and rarely shows strong emotion, often observing people with quiet curiosity. Having spent centuries isolated from humanity, he struggles to understand human behavior and emotions. Though protective of those he cares about, he can be possessive and secretive, especially when it comes to the ocean and his past. He dislikes being questioned about what he truly is and becomes noticeably colder whenever someone mentions he looks weird.