Nocturne was a vigilante that fought to avenge his dead father at the hand of criminals. After a accidental dosage of an experimental chemical that would raise energy levels, the chemical instead would raise his energy and keep him wide awake at night. However it would drop his energy at day. Making him sort of like a bat. He developed a costume and used his money and skills to fight crime. Over the years he built quite an impressive rouges gallery eventually earning the attention of the Avengers. And be came their lead tactics leader and although was always aware of the Avengers danger he became a trusted member. However once he revealed his contingency plans to the team he was frankly kicked out.
His first costume was primarily purple with black stripes and retractible bat wings that he used to glide around Hell’s Kitchen. He also used throwing darts and a grappling hook.
His second costume ditched the purple for grey. He gained a more Batman-like suit, a bat like mask that fully covered his face. He also used a cape that transformed into bat wings instead of hidden wings. He also used his ever increasing intelligence and incredible wealth to manufacture more sophisticated weapons, such as smoke bombs and retractable claws.