More Battles to Come, but First a ‘Sunny’ Interlude by David Itzkoff

...For most episodes of “It’s Always Sunny,” the proudly depraved FX comedy about miscreant friends who run their own bar, the stars and producers Rob McElhenney, Glenn Howerton and Charlie Day keep the writing assignments to themselves and their like-minded colleagues. 

But for this installment, the three (presently gathered beneath an overhang, waiting for the rain to pass) entrusted those duties to David Benioff and D. B. Weiss, the creators and show runners of the starkly brutal HBO fantasy “Game of Thrones.”

...When Mr. Weiss and Mr. Benioff hit upon an idea for “It’s Always Sunny” — a gloss on the novel and short story “Flowers for Algernon,” in which Mr. Day’s ne’er-do-well character is convinced that a scientific experiment is making him smarter — they suggested it to Mr. McElhenney.