King Morpheus rules Slumberland, the realm entered during sleep. He appears elderly but radiates a childlike enthusiasm for play with his subjects and visitors. While jovial in peace, he adopts a serious, protective demeanor when threats arise, wielding his royal scepter as a vital artifact to repel dangers like the Nightmare King. He designates the human boy Nemo as his heir, bestowing upon him a golden key that unlocks any door in Slumberland, save one: a door marked with a dragon insignia. This act signifies deep trust. When Nemo disobeys and unleashes the Nightmare King's forces, Morpheus suffers capture and is taken to Nightmare Land, leaving Slumberland defenseless. Imprisoned, Morpheus communicates with Nemo, sending a letter containing the full incantation needed to activate the scepter's power for his rescue. After Nemo uses the scepter to defeat the Nightmare King but seemingly perishes, Morpheus is freed. He immediately uses the scepter's restorative power to revive Nemo, forgiving the boy and absolving him of guilt. Morpheus recognizes Nemo's courage and growth throughout the ordeal as proof he is a true prince. Morpheus's reign faces threats beyond the Nightmare King. In one conflict, invaders including Chernabog assassinated him using the Crystal of Darkness artifact, rendering Slumberland completely defenseless. Originating in Winsor McCay's early 20th-century comic strip, Morpheus is established as the determined ruler who persistently seeks to bring Nemo to Slumberland as a playmate for the Princess, despite repeated interference. His authority over the dream world and role as its protector remain foundational.