In Curse Of Strahd, Cyrus cooked dinner for the Heralds of Dawn, which he did out of Barovian commoners in an enchanted cauldron. Afterwards, he was summoned to take them to the castle's guest chambers after their dinner, but found that they questioned him relentlessly. Particularly, they wanted to visit the castle's catacombs, so Cyrus attempted to lead them to an elevator trap near his kitchen, but was the only one affected by the trap's magical gas. Mormeros Fayan woke him up with myriad threats, and the mongrelman let them out in front of the guest chambers before bounding away, not telling his master of the incident out of fear.
Over a month later, Cyrus had to prepare a feast for a far larger number of guests during the events of the Vasilkan Wedding. He attempted to hide from his family as they skittered around the castle, knowing that any of them could turn on him. However, when the wedding finally reached it's blood-soaked conclusion, Cyrus for the first time felt pity and remorse for abandoning his family. The master he served so loyally had killed everyone he had ever known; he was the last living Belview.
On a final mission, the Heralds would sneak around an even-more-insane Cyrus as he ran about the castle, an adventure which culminated in the Slaying Of Strahd.