The Drekavac is a demonic spirit tied to the souls of unbaptized children, known in Balkan legends for its bone-chilling scream. It is a lost soul that alternates between grief and rage and can infect others with its scream when it reaches a terminal volume. The spirit was accidentally summoned by Lysa Pascal and Connor Green when they touched the Stone of Kraovic, which burned wolf-like marks into their hands.

Lysa and Connor accidentally summon the Drekavac by touching the Stone of Kraovic in the library annex, which results in them being marked with wolf-like burns. Lysa is skeptical about magic, while Connor is excited about the discovery, and together they become central to stopping the Drekavac's threat.

Vikram Chamberlain is a Librarian who was lost through time for centuries until rescued by Jacob Stone. In the episode, Vikram restores his library annex in his old castle, which inadvertently unleashes the Drekavac. He explains the nature of the Drekavac to the team and is deeply involved in the efforts to contain the spirit.

The team discovers the symbol of Gregor’s Hammer on a door in Belgrade and fears the cult has survived into modern times. However, they find only a heavy metal band named Gregor’s Hammer, whose lead singer, a Lynch descendant, is connected to the Drekavac possession history. This leads the team to investigate further at the venue where the band is playing.

Charlie is a fallen Guardian who joins the team to help keep magic in check. She is somewhat mysterious, with a past that includes regrets, and was thrown into the mission by Jacob Stone. Charlie assists Vikram, Lysa, and Connor in confronting the Drekavac and managing the magical chaos unleashed in 2025.