Jarvis Adeola was the brother of Tanya and Damon, and son of Vivian and Jasper. He and Damon were born two years after their parents got married. (TV: Nightvisiting)
Jarvis would play Xbox with his siblings. According to Tanya, after their father's death, Jarvis would say, "Do you remember how bad Dad was at this?" and Damon and Tanya would say, "Yeah." They'd laugh and keep playing. (TV: The Coach with the Dragon Tattoo)
In 2016, on the second anniversary of their father's death, Jarvis, Damon and Tanya went with Vivian to visit his grave. (TV: Nightvisiting)
Corakinus the Shadow King attempted to kill Jarvis and Damon in the Coal Hill library, but Miss Quill fought him off. Tanya told them to take a train to their grandmother's place. (TV: The Lost)