Comic book writer and screenwriter Frank Miller – whose work includes “300,” “Sin City” and “Batman: The Dark Knight Returns” – returned this week to Lucca Comics and Games, an event that spans the gamut of geek culture and pop entertainment. As well as speaking at the event, to coincide with the 40th anniversary of “Batman: The Dark Knight Returns,” Miller also introduced “Frank Miller – American Genius,” Silenn Thomas’ documentary about his impact on popular culture. Related Stories Variety spoke to Miller about politics, art and why he’s relieved there are fewer comic book movies this year. Would you…