Flintstone is a survivor of the 'waves' and became a soldier of Camp Haven. He is the same age as Ben Parish and is described as having a big head and a unibrow.
Flintstone was the first squad leader of Squad 53. However, when Ben Parish stood up against Reznik for his mistreatment of Sam Sullivan he was bumped down and Ben was made Squad leader instead. He was killed when he mistakenly activated his tracker's kill function and fried himself in front of his squad.
Flintstone was a member of Squad 53 since Ben Parish/Zombie's arrival at Camp Haven. He was the squad's leader until Sam Sullivan/Nugget was brought into the squad and suffered abuse from Reznik. Zombie spoke in defense of Nugget but didn't back down from Reznik which made him replace Flintstone with Zombie as the squad leader.
When Tank went 'Dorothy', or crazy, Flintstone went to subdue him when he pulled out a gun. After Tank was killed, Ringer was brought into the squad. Ringer mentioned that she loved chess. Flintstone went on to cockily say that he preferred strip poker and tried to offer her a game which earned him a strike to the neck where she spat that she didn't like sexist remarks.
During the squad's first mission, Flintstone didn't like where they were positioned. When they were pinned by enemy fire and a sniper, Ben had them all pair off before they were to run putting him and Ringer together. Ben then blew the tanker diesel truck they had hid behind. The explosion sent a piece of metal flying into Oompa's back which inevitably killed him and Teacup was shot in the leg. Flintstone wailed on Ben, telling them that they shouldn't have stayed there as long as they did and was starting to question Ben's orders.
When Ben and Ringer, returned with news that they killed Reznik, who had been the sniper shooting them, and with the device monitoring them and could activate the killswitches in their trackers Flintstone refused to believe it. He claimed that they were going Dorothy and had killed their commanding officer. Ben mocked him and told him that if the button on the device was activated he would die and Flintstone wanted to disprove him so he took it from Ben's hands and pushed the button. Flintstone immediately seized up and dropped to the floor dead as the tracker fried his brain to everyone's horror. Ben took the device from his dead hands with an urge to punch him for his stupidity.
Ben took his gun and shot Flintstone's corpse in the head to help him sell a story to Vosch that Flintstone and Ringer had gone Dorothy and had tried to kill him as they killed Reznik. It also hid the evidence that he had been killed by the killswitch. The soldiers managed to recover Flintstone's corpse and Ben told Vosch that he had shot Flintstone before Ringer had shot him and took the whole squad with her to go rogue.
Ben Parish had been very out of it after he was attacked and captured by Camp Haven soldiers. He thought that he was dead and was seeing the images of his lost squad members including Flintstone.
In the film, Flintstone manages to survive as he calmly listened to Ben and Ringer instead of fought against them.