Gren Tal'Dorei

 is the son of Sovereign Uriel Tal'Dorei III and Salda Tal'Dorei. As an NPC, Gren is played by Matthew Mercer.

Background
Shortly before Vox Machina arrived in Emon for the first time, there was an attempted assassination on Uriel's family, which was thwarted by General Krieg. Following the attempt on their lives, the royal family grew strange and withdrawn, keeping Uriel away from the Council of Tal'Dorei.

After being barred entry to the palace for seven days, Allura Vysoren took Vox Machina to her home, the Ivory Tower, where she and Keyleth scried on the Palace. Their vision revealed that Gren, his mother, and his sisters were all under the influence of a demonic force and had been addling the mind of Uriel to use him as a mouthpiece for their plot.

After slaying Brimscythe—the draconic true form of General Krieg—Vox Machina returned to the palace, where Allura informed them that the evil feeding on the throne was growing more bold. With her help, Vox Machina infiltrated the palace as dark clouds began gathering overhead.

As they entered the throne room, they saw Uriel sitting upon the throne, surrounded by his possessed family. Vox Machina managed to banish the shadows from within their bodies, but then the dais below the throne began glowing a deep red, causing the throne itself to crack.

A glabrezu named Juurezel emerged and Vox Machina did battle with it. During the battle, Pike was killed, and as soon as the fiend was slain the party hurried to a nearby temple of Sarenrae to resurrect her. When Vox Machina returned to the throne room, they discovered that the royal family was still lying catatonic on the floor. After inspecting their bodies, they realized that their souls were missing—and without souls, their bodies were failing. Remembering the four glowing orbs they had retrieved from the Clasp's headquarters after killing Modeth Lai, they identified the orbs as soul jars. Through a rigorous and intense evening, Vox Machina successfully restored the souls of the royal family.

Sovereign Uriel Tal'Dorei threw a Winter's Crest Festival in which Vox Machina were celebrated as heroes. During the festival, Gren spoke with a strange boy who had black hair and golden eyes. Vox Machina saw this, and recognized the boy as the one they had been hearing rumors about—rumors that other children seen with him mysteriously vanished soon after. The adventurers rushed after the boys, following them into an alley and then through some kind of portal.

The portal lead them to a large island drifting through the Astral Plane and surrounded by a perilous bramble forest. Fighting their way through, Vox Machina eventually came upon a gothic mansion in the center of the landmass. They made their way to the inner library, seeing many children cleaning nervously throughout the building.

When they found him, the golden-eyed boy stood from his chair, letting the illusion fade into a man with long black hair and golden armor with four children attached to him by chains around their necks. The Dread Emperor attacked the party with fierce magic, commanding the mind-controlled children to attack as well. As Vox Machina attacked the man, they realized that any damage done to him was also done to the chained children. One boy was killed as Keyleth tried to yank him away from the Dread Emperor with a Grasping Vine, causing his neck to snap under the pressure. Even so, the party eventually killed the Dread Emperor and returned the remaining children, including Gren, to their families.