Cooper is a wolf-dog pup who Professor Karsten experimented on, giving him a new strain of canine parvovirus. In the Virals' attempt to save the pup from the LIRI labs, they were exposed to the virus and became infected, ultimately giving them 'super-human' abilities. Cooper's mother is a wolf named 'Whisper ' and his father is a German Shepherd of unknown origin, dubbed 'Polo'. He also has a brother named 'Buster.'
When Cooper was still very young he became trapped in a deep hole in the woods of Loggerhead Island from which he couldn't escape. Tory, Ben, Shelton , and Hi happened to be lounging on nearby Turtle Beach when they heard strange noises comming from the woods. Tory braved Coopers mother, Whisper, in order to rescue the pup. At the bottom of the hole was a broken barrel stamped with, "Cooper River Boiled Peanuts." This is where Tory got Cooper's name from and she often calls him 'Coop' for short. The girl then returned Cooper to his family and they retreated into the woods once more.
Later Tory and the gang decide to go looking for the wolf-dog pack on the island, but when they spot them they notice that Coop is missing. After being attacked by some rogue monkies, they stumble accross an old dog tag. They cannot read the inscription so they return home and concoct a scheme to break into the LIRI after hours in order to use the lab's cleaning equipment to remove the years of filth from the tag. Upon breaking into the research facility they find their way into Dr. Karsten's secret lab. They soon discover that Cooper has been imprisoned here.
Tory reads the tag on Coopers cage in the lab discovering that he has been infected with Parvovirus XPB-19 which is a disease deadly to dogs, but normally harmless to humans. Another form on the cage said that the pup was scheduled for immediate termination because he was unresponsive to treatment. This form was signed 'Marcus E. Karsten.' The four friends escape with Coop and stow him away in their Bunker back on Morris Island where they nurse him back to health. It isn't long before the group begin to come down with some sort of illness.
It turns out that the strain of parvovirus that Coop had been infected with was infectious to humans as well. Tory, Ben, Shelton and Hi soon recover from their illness, but they discover that certain things can trigger 'flares' which enhance their senses. They have clearer vision, more sensitive hearing, a better sense of smell and even enhanced strength, speed and endurance.
At the end of the first book the Virals decide that it is best to return Cooper to his family as he has recovered fully and is no longer contagious. They return him to Loggerhead Island to be with his family. As they jump on board Sewee and begin to leave, Coop swims out to the boat. From that point on Cooper was part of their pack and they looked after him as one of their own.
Cooper was taken in by Tory and lived at her house as a pet. Kit, Tory's father, is tolerant of Coop and has actually shown to take a liking to the wolfdog. Kit's girlfriend, Whitney, however, despises Cooper and often tries to keep her distance. She also shows some fear and disgust towards Coop, the fear first shown in Code when she yelled that she thought Coop was about to attack her, to which Tory replied 'Try to protect your throat.'
In Code it is revealed that Cooper is the 'touchstone' of the pack and therefore amplifies the abilities of the Virals, particularly their telepathy powers. When Coop is present, the Virals function the best, as shown in Code when they closed in on the Gamemaster and in Exposure when they took down Detective Hawfield in the woods.