The Lost Shepherd

 is a quest in Torment: Tides of Numenera.

Synopsis
Erritis has been acting strange ever since we entered the Valley of Dead Heroes. I need to figure out what's bothering him. Erritis spoke fearfully of alcoves in the Valley of Dead Heroes. Maybe searching the Valley and finding the alcove he's "not afraid of" will explain why he's behaving strangely.

Walkthrough

 * When you enter the Valley of Dead Heroes, Erritis will start to freak out. Investigate the valley. You want to find the glowing, green alcove on the upper-right minim. With Erritis in tow (use the Bronze Sphere to spawn him if you didn't bring him along), touch the herder's crook in the alcove.
 * A reflection will form in the Labyrinth. Enter it (bubbling acid pool or the feretory in Miel Avest) to find Erritis' reflection, which will explain what happened in the alcove and ask for help.
 * Help can be found in the Bloom, in Chiurgeon's Slump. Talk to Demeray or Obervich to learn that a nano-demon specialist lives in the Old Slave Block. Head there and talk to Skoura.
 * In exchange for agreeing to helping her (What the Winds Took), she will teach you to influence the Audience possessing Erritis.
 * Head to the Labyrinth, talk to Erritis, and decide whether to empower the Audience or make it release Erritis. If you choose the former or never resolve the quest before confronting the First, he will never be free of the Audience. Otherwise, you get the chance to free him permanently later on, in the Crefton Fathom.