King of the Hill showrunner Saladin Patterson has clarified that the sudden end of Nancy Gribble and John Redcorn's long-running affair in season 15 was not a response to the real-life death of Jonathan Joss, the actor who voiced Redcorn. Joss was murdered by a neighbour on 1 June 2025, shortly before the show's season 14 premiere, and it might have appeared that the storyline change was a tribute or reaction to his passing. Patterson explained that the relevant episode had in fact been written and largely completed before Joss died, and that Joss recorded his lines for it beforehand, meaning the timing was coincidental rather than deliberate.

In season 15 episode 5, "The Best Little Marriage in Texas," Nancy tells John Redcorn that her "headaches" — the couple's longstanding euphemism for their affair — have stopped, prompting a bittersweet farewell scene. Patterson said the writers, alongside creators Mike Judge and Greg Daniels, deliberately left the door open to bring the John Redcorn character back, as happened after the affair first ended in season 4. He added that the real motivation for ending the affair was creative: to explore how long-married couples such as Nancy and Dale, and Hank and Peggy, reassess their relationships later in life.