Jack Quaid bounds up the stairs of Manhattan’s Midtown Comics like a Golden Retriever on a long-promised walk, his plaid winter jacket fluttering behind him in the January chill. Sandwiched between a 99-cent pizza joint and a smoke shop, the Times Square institution is one of the largest stores of its kind in the world — which makes it all the more surprising that the 32-year-old self-professed comic-book geek has never paid a visit before. “Every time I’m on location somewhere, I always Google the nearest comic book store,...