Along with Abe Brown and Lin Sun, Bob Diamond was one of the most skilled students attending the martial arts school run by sensei Master Kee. Kee gave the three students each a jade talisman in the shape of a tiger’s head and forepaws, when he sustained mortal injuries due to an attack by a group of ninja terrorists. As the Sons of the Tiger, the three martial artists avenged their master’s death, and became a group of adventurers for a while.
In the course of avenging Kee's death against the Silent Ones, the Sons encountered a woman named Lotus Shinchuko, who was under control of the Silent Ones. The Sons saved her, and she became romantically involved with Bob Diamond. She proved to still be under their control however, as she attacked him and then attacked Abe Brown. Lin Sun discovered and removed a device from her neck that the Silent Ones were using to control her.
Later, Bob became an actor, working on a movie filmed in San Francisco's Chinatown. When people involved in the film’s production began turning up murdered, he helped track down the person responsible.
Diamond purchased a Chinatown building to be the new martial arts school for the Sons. They were contacted by a private detective known as Blackbyrd and a representative of the National Citizens Liberties Union to help investigate reported atrocities at the New Troy State Prison.
As the Sons became involved in helping out superheroes, such as Iron Fist, Spider-Man, and the Human Torch, Lotus began to draw away from Bob and became closer with Lin Sun. This led to a fight between the group which ultimately tore them apart.
Bob renewed his acting career, and became the sparring partner of Iron Fist to keep from losing his skills. He also began a romantic relationship with Colleen Wing. When Master Khan stole the tiger talismans, he badly injured Bob Diamond. On recovering, he began to assist Iron Fist and Luke Cage regularly as part of their Heroes For Hire operation.