Darius was the son of police officer Harry Pike. Harry often brought Darius to his precinct house, which would later become Gryffen Manor. After the Department's CCPCs made human police obsolete, Harry became obsessed with revenge, leaving Darius and his mother to focus on his mania.
Darius was employed by The Department to keep an eye on the Professor. He was also his personal assistant and tended to his car, Mariah. He met criminals Starkey and Jorjie after encountering K9 and Jixen. He informed the CCPCs. He went with K9 to rescue Starkey, though he still didn't like him. He once almost destroyed London when he accidentally unleashed a swarm of alien nanobots.
An accident in the STM resulted in Jorjie being sent to 23 November 1963. K9 and Starkey were sent to retrieve her. They encountered Darius' great-grandfather, William Pike and saved him from the clutches of Barker, a MI6 agent with a surprising resemblance to Thorne, preventing Darius from being erased from history. Gryffen, with June's help, brought them back.
Like almost all of Britain's kids, Darius was a huge fan of the latest VR game, Little Green Men. Darius, Jorjie and millions of other children, were almost turned into Etydions until June convinced the last Etydion to stop what he was doing.
Darius met his estranged father when he and his group, The Last Precinct, attacked Gryffen Manor, using it as a staging ground for their plans to disgrace the CCPCs. Although Darius helped derail those plans, leading to their arrest, he and his father parted on civil terms.
Soon after, Darius was approached by Thorne, who claimed that his father was suffering in prison. Thorne offered to make his sentence more bearable in return for K9's regeneration unit. Darius convinced K9 to go along with it, only to be double-crossed by the group.
When a strange phenomenon in the STM threatened Earth, Gryffen sent Darius to collect June. Shortly after, CCPCs in the area were given new orders that human personnel had no authority. When the two were confronted by two CCPCs, June saved Darius by grabbing a large gun and destroying them. They made their way to the STM control panel. Darius pulled June back just as the STM exploded, saving her life.
Darius later heard that K9 was about to die. A tearful Darius told him he was the coolest thing to ever happen in his life. As per its programming, K9's regeneration unit homed back to him, allowing him to renew himself. Darius was delighted to see him alive again.
Darius was a hard worker,and loyal to the the professor, whom he saw as a father figure. Being an employee of The Department, he did not dislike and distrust them as much as Starkey and Jorjie. He would willingly go to them for help on occasion. He showed great care for Gryffen, comforting him at bad times and going off to rescue him when he was kidnapped. He initially disliked Starkey, believing his troublemaking ways would only bring the Professor strife, but they became good friends. Darius and K9 sometimes argued. He had a crush on Jorjie, and was heartbroken when she confessed to him she had a crush on Starkey. He was very attached to Mariah, spending most of his free time polishing and working on her and was angry when it appeared K9 had damaged her.
Darius was something of a pragmatist, abandoning his friends' plans when they seemed too outlandish or likely to fail and seeking help elsewhere. He also had a habit of concocting get-rich-quick schemes, usually involving alien technology.
Darius suffered from claustrophobia and coulrophobia.