Yellowstone's Luke Grimes is adding fuel to the fire that a major loss is coming for Kayce on the spinoff Marshals. Grimes, 42, teased his character's arc in the first season of CBS' upcoming show, telling TV Insider on Tuesday, February 17, "Being a cowboy was at the heart of his character. He wanted his little slice of heaven and some cattle. Every other Dutton wanted the world." The actor went on to hint at an onscreen shakeup.