- "Radiant Garden shall not fall under the likes of you."
Dilan appears with Aeleus, both guarding Ansem's castle in Radiant Garden. Ventus first encounters them while he is looking for Mickey Mouse, but they refuse to let him in saying that castle is closed. Dilan suggest that Ven should go home before the monsters get him. Aeleus then spots an Unversed, and both guards are about to charge. Ventus chases it, despite the guards protests. Both were about to join Ven, but Even comes and openly wonders what will become of the castle if they leave. Aeleus and Even begin to argue, but Dilan reminds Aeleus that the castle comes first and both resume their watch. letting Ven take care of the Unversed.
Later, Braig brings Dilan and Ansem to an amnesic Terra, along with the Keyblade and armor of a Keyblade wielder. Terra can only remember his possessor's name: Xehanort. While Braig takes Xehanort to the castle, Dilan carries the armor and Keyblade for Braig.
Between Kingdom Hearts Birth by Sleep and Kingdom Hearts 358/2 DaysEdit
About a decade prior to Kingdom Hearts, Dilan was still one of six apprentices to the ruler and scientist of Radiant Garden, Ansem the Wise, alongside Braig, Even, Aeleus, Ienzo, and Xehanort. Worried the Darkness in people's hearts would eventually consume his world, Ansem began performing tests on Xehanort's heart. Eventually, he created a laboratory in his castle's basement for such experimentation, by the urging of Ienzo. However, Dilan and the other apprentices had their own intentions for the laboratory, and began conducting inhumane experiments on the human heart and the darkness within it. Such experimentation led to the creation of Heartless. Ansem quickly discovered their secret experiments, and immediately ordered them to stop. One day, after being advised to review their research data by King Mickey, Ansem found that the effects of their experiments had become irreversible. Eventually, Dilan and the other five apprentices dabbled too deep into darkness through their continued experiments. Dilan, along with the others, was consumed by the darkness, producing a Heartless. However, the apprentices all had strong wills, and so Dilan also became his Nobody, Xaldin. The six Nobodies formed Organization XIII, and banished Ansem the Wise to the Realm of Nothingness.
Dilan returns following the destruction of his Heartless and Xaldin. He wakes up in Hollow Bastion with Even, Ienzo, Aeleus and Lea. Having not fully recovered, he rests with Even as Ienzo and Aeleus search Ansem's study.