The Elden Ring Thiollier quest is one of the more important ones you'll encounter among Miquella's oddball companions, relating as it does to St. Trina and her connection to Miquella. In case you don't remember, or are a person with a normal amount of Elden Ring lore in your brain, St. Trina is the goddess of sleep and at this point, it's basically confirmed that she's an alter ego for the Empyrean Miquella.
Thiollier is a worshipper of this saint of slumber but with Miquella casting off his various bits around the Land of Shadow, he wants to determine the fate of St. Trina and drift off into a peaceful eternal slumber. Here I'll explain each step for completing Thiollier's quest in Shadow of the Erdtree—be warned, this guide will include spoilers for his questline, particularly in the final section.
