As part of Marius's companion quests in you'll learn more about his history and childhood in Galawain's Tusks. Eventually, he'll talk to you about his memories of the region and will explain that he felt the people there knew something he didn't and were keeping it from him. He will then direct the party to the Lost Village north of Solace Keep where he grew up. This triggers the "Chorus of the Lost"companion quest in Avowed, which will finally give you some insight into Marius's troubled past.

When you approach the Lost Village, Marius will start to have an anxiety attack about being back there. Exploring the area, you'll find Marius's mother's amulet and eventually run into Iancu. This Dreamscourged old friend of Marius's informs you of the cult leader Razvan, a zealot who convinced the village people to commit mass suicide, and who might still be alive in a sealed-off temple nearby. Iancu will give you a key to Razvan's hut, which is where you'll find Razvan's journal containing the cantec to open the sealed door and decide Razvan's fate once and for all.

Once you find Razvan inside the temple, you'll learn exactly what he's been up to all this time. Razvan is actually another one of Avowed's Watchers, though he doesn't realize it, and believes he could "ascend" the people in the town. Things didn't go according to plan, and now he's haunted by their deaths, suffering down in the temple alone. You have the choice to attack him right away, though you'll miss out on some interesting Marius dialogue. If you do, Razvan isn't a difficult enemy, but he doesn't have any notable loot on his corpse after taking him out.