‘Alter Ego’ by Alex Segura. Flatiron, 320 pages, $28.99 It’s been a while since comics and graphic novels were just for children. Look no further than the plethora of Marvel Universe movies that attract teens, and adults of all ages, and, of course, some children. The stories in comics and graphic novels make good on their promise of action-packed stories, heroic characters, the never-ending search for justice. Alex Segura returns to the comic book world in his emotionally charged “Alter Ego,” which evocatively looks at how art is created, as well as finance, sexism and dual personalities.