Kingdom Hearts: Child of the Keyblade
Disclaimer: Any kingdom heart or Disney characters in this fan fiction belong to Disney and Square Enix/Squaresoft.
NOTE: Since the "World of Kingdom Hearts' does not have a name, I named it Glanis.
After the defeat of Xemnas, Twilight Town returned to peace and Sora could return to the Destiny Islands. Organization XIII was destroyed with Xemnas to confirm the 'eternal' happiness of the generations to come. However, the protection of the worlds could not last forever. 30 years later, King Mickey, ruler of Glanis, passed away of old age, leaving Queen Minney to die brokenhearted not too long after.
Sora, Riku and Kairi dwelled in their home unaware of what was happening to the kingdom. Years past and soon, Kairi had a child to Sora. They knew not of his significance at the time. Years had passed and Riku fell ill to his dark side. Soon, Riku killed himself to end the madness. Stricken with grief, Kairi and Sora sought counsel with the King, only to be informed of his death.
King Mickey's passing meant the end of appointment of Keyblade wielders. The keyblade wielders protected the world from harm and from further threats, leaving Sora as the only wielder left. Sora locked the door to light so it could never be used again with the Nobodies commanded by Organization XIII and the heartless behind the door. As a result, the Keyblades vanished for no one could use them. The generation had ended vulnerable to more evil than ever before.
One century later, the peace was once again disturbed. A new militant group called "The Alliance" became the center of evil in the world. It chose to despise the light and became the new darkness without purpose but to destroy Glanis. Without the keyblades to protect them, Glanis was doomed.
The settlements of Radiant Garden and Twilight Town became a united front to battle The Alliance, but they were losing the battle. However, deep in the Ansem's mansion slept another hero. The last of the descendants of Sora and Riku, a child slept that could bring peace once again to Glanis. His destiny lie in the depths of the world. The remains of what used to rule the evil. He was the only one that could save or destroy. This is his story, the child of the Keyblade.