- Father: Sampson Gray
- Half-Brothers: Gabriel "Sylar" Gray and Gabriel Silvestor.
- Half-Sister: Rachel Max
- Nephew: Oris Gray
- Partner: Elle Bishop
- Children: Lily Bishop and Jacob Bishop.
Nothing interesting happened to Robert until age 12 when he ran away after finding out that the father who'd raised him wasn't his biological father. After he turned 13 and his powers manifested he didn't return home for fear of being branded a freak. He tried not to use his powers but eventually became more and more reliant on them, despite being unable to use them for extended periods of time.
At age 22 Robert brought a man who had jumped off a building to a hospital where Gabriel worked, unaware that he had attracted the attention of Sylar when he unknowingly used a power in front of him. Sylar followed him and on the street began to fight him for his ability. Robert was going to lose when he was assisted by Rhia Jones and Gabriel. With their help he defeated Sylar. Robert found out about the Company and began to break into their bases, when he found out about the virus he tried to get it but failed, after retreating he was once again attacked by Sylar, which made Robert accidentally Time Travel to 1671. Here he met Hiro Nakamura and Adam Monroe, then using the alias of Takezo Kensei. He helped with Hiro's quest to make Kensei a hero, and in return Hiro taught Robert the ways of the Samurai (including how to use a sword), how to use his powers more successfully, how to become a hero and the language Japanese.
When Adam saw Hiro kiss Yaeko, Kensei knocked out Hiro and Robert and drugged them; this caused Robert to teleport back to the future. Still high on Opium, he met Elle Bishop and tried to help her capture Peter Petrelli and Rhia. After failing to do this Elle captured Robert. Robert awoke in a Company van getting transported to another facility, he broke out and teleported to Tokyo, while walking down the street Hiro teleported to Robert and returned his sword from 1671.
Robert teleported back to the company base where he was re-captured. In his escape attempt he released Sylar, who after failing to kill Robert and Elle went to get Claire Bennet. After Sylar had successfully taken her power Robert arrived and the two fought, Robert eventually winning. He brought Sylar back to Primatech and locked him up. Elle helped to clean up all the blood and started to teach him to use her power, after that they had sex.
After Robert woke up he received a vision about the virus and deciding he would need the power to heal people. He visited Jeremy Greer and mimicked his power. After that was the day that the virus was released. Robert arrived at the Company base after Hiro had been knocked out, and after healing him he teleported to the vault where Peter had already opened it. He and Peter fought for a bit, then a lot of other people arrived, but they all failed to prevent the release of the virus.
After the virus was released, Robert was quarantined in Odessa trying to heal everyone, but his regenerative blood failed to do anything. Sometime during the chaos, all the Company prisoners were released, Sylar amongst them. Robert fought Sylar but was unable to re-capture him. Eventually he enlisted the aid of 4 other Level 5 prisoners to help him capture Sylar, but Sylar defeated them and took most of their powers.
After getting radiated by Peter to prevent the virus from travelling with him, Robert left Odessa and went to Elle. However, she broke up with him on Valentines day. He decided that he didn't want to remember her and risk himself becoming like Adam, so he went to The Haitian and had his memories removed then returned to Odessa. He was still left feeling inexplicably lonely and depressed, which led to his suicide attempt. It failed due to regeneration.
Rhia found him covered in his own blood and tried to convince him that he still had plenty to live for. She knew that Elle, her sister, was currently pregnant, but couldn't tell him because she'd promised Elle not to do so. After this Robert gave up trying to kill himself, and he decided to leave and get an apartment in New York. Due to his emotional attachment to Elle, felt her pain in childbirth and when she murdered. This brought his memories back. He phoned Rhia and she admitted to him that he was a father. He went to find his children who were being kept by the Company, but when he was close to getting them his children from the future stopped him from rescuing their baby versions. They informed him that he shouldn't risk altering the present course of their lives. However, after the Rhia murdered Bob Bishop avenging her sister, Robert went to get his children. Soon after he had rescued his children Rhia and Peter brought Elle back. She at first tried to leave again, but the pair eventually fell back in love.
After a few days of relative normality it was discovered that the government was going to start hunting evolved humans, blaming them for the virus. Robert was warned and managed to escape. He and several others fled to Russia where they bought a house and set it up as a place of safety. Then a group of them brought down a plane that was transporting captives.
After this Sylar found the house and attacked Lily, Jacob, Elle and Robert. Elle decided to track Sylar down and kill him. They found him at the hospital after the birth of his son and they fought. Sylar held them off until B26 soldiers arrived, breaking the fight up, after the soldiers were killed Robert went to face Sylar alone, but ended up making a deal with him that they wouldn't attack each other's families.
When Elle learned that Robert had lied to her about what happened, she got infuriated and wouldn't let Robert see the kids, claiming he'd endangered them, but eventually they kissed and made up. Later Sylar came back in order to ask for help in stopping being a killer. He was trapped in his own mind by Matt, Robert discovered him and went in his mind as well, spending what felt like 5 years in there. After they came out Robert told Elle about it, she got angry and banned him from the kids again, but eventually they made up once more. When out shopping Elle got captured, but Robert led a raid on a B26 prison where Elle was released.
After B26 was destroyed and the hunting of evolved humans ended, Maya cured the virus, but doing so revealed evolved humans and abilities to the world. Robert and Elle bought a home outside NY. Robert then became one of the founders and leaders of The New Company, set up to deal with threats to and from evolved humans. One of these threats was an organisation made up from ex-B26 employees. When out raiding one of their bases his SWAT team turned on him and shot him, then locked him up with a few people who didn't side with them, together they broke free and Robert destroyed their base. On another mission, Robert was temporarily possessed by their target, but Elle noticed the possession from his projected thoughts and helped him regain control. Robert also finally proposed to Elle, having been planning to do so for a while. They have now been engaged for years.