Flynn grew up as a normal American teenager, unaware that both he and his sister, Fiona, were of Inhuman ancestry.
Flynn was created by writer Matt Kindt and artist Paul Davidson. He first appeared in Inhumanity: The Awakening #1.
Major Story Arcs
Prior to Thanos' invasion of Earth, Flynn was a normal teenager. During the invasion, the King of the Inhumans, Black Bolt, detonated a bomb and crashed the floating city of Attilan into the ground. The bomb unleashed Terrigen Mists which all the humans on Earth who had Inhuman blood to experience Terrigenesis by entering a Terrigenesis Cocoon. They entered human and emerged with new powers and appearances.
Flynn was one of those new Inhumans, much like his sister. When Fiona decided to kill herself as a result of being bullied, Pixie, Finesse, Quentin Quire, and Striker arrived and helped her acclimate to her new abilities. Fiona took the heroes to Flynn's room to help him as well, but he was gone, leaving only a giant hole in the ceiling.