Despite going through numerous hiatuses throughout its run, Berserk remains one of the most highly praised manga series among fans. It covers the darker themes that come with a fantasy setting, and has even spawned several memes like "Griffith did nothing wrong" and Sad Guts.
While the future of Berserk remains in limbo due to the passing of creator Kentaro Miura in May 2021, fans continue to talk about and theorize on all the information and characters in the 364 chapters released so far. The Moonlight Boy and his connection to the main characters is the latest big reveal to have come out before the story's fate came into question at the time of writing.
The Moonlight Boy is an entity that appears on the night of a full moon and disappears the following morning, showing himself as a mute human child with long, dark hair. The first time he's seen in Berserk was when Guts was falling under the influence of the Berserk Armor, which caused him to begin losing himself to his inner darkness.
The Boy, however, appeared and was able to ease the Armor's influence on Guts and pull him back to reality. After Casca later found the boy while walking along the beach, they shared a relationship like that of a mother and son. This is because the Moonlight Boy is the embodiment of the unborn child, also known as the Demon Child.
The Demon Child was the result of Griffith's assault on Casca as Femto, who was pregnant with Guts' child. The result caused the fetus in her body to become tainted by evil and be born prematurely after the events of the Eclipse. The Demon Child was found and eaten by the Egg of the Perfect World during a ritual, which caused the two to fuse together and form a new, corporeal child vessel for Griffith to reincarnate into. Because the Demon Child was an unplanned part of the ritual, its consciousness still resides within the vessel -- though it only appears and takes control during the full moon, when magical abilities are at their strongest.
While the Moonlight Boy's role in Berserk's dark fantasy world hasn't been revealed other than his relationship to Casca, Guts and Griffith, it could prove to be the major turning point in the series' final battle. With both the Boy and Griffith inhabiting the same body, it could come down to who will take control and which consciousness is stronger. The Boy has magical abilities, being able to ride the branches of the World Spiral Tree and controlling astral creatures to some extent.
Any other abilities the Boy might possess could prove to be the key to defeating Griffith once and for all. Griffith's recent selfless acts might be influenced by the presence of the Moonlight Boy within the vessel, so there's a possibility this influence may come back in a major way if Berserk continues.
