As prolific as Shonda, Ryan and Chuck, the lower-profile showrunner behind today's network hits ('Blindspot') and hunky superheroes ('The Flash,' 'Arrow') is not too big to keep pushing Hollywood's comfort zone on sexuality, abortions and so-called taboos. Greg Berlanti settles into a bank of couches in his office on the Warner Bros. lot, tucked in between brightly colored pillows with hand-stitched logos for two of his shorter-lived television series, No Ordinary Family and Dirty Sexy Money. There are eight more pillows throughout the spacious office, one commemorating each of his film or television projects. His mother has them made for...