Before you can embark on the epic adventure to unlock Peter Pan in Disney Dreamlight Valley, you need to complete the Poetic License quest and have the A Forgotten Name quest available. To do this, you'll need to meet the Forgotten anywhere in the valley, where they'll tell you that they've found a red feather outside of Skull Rock, which the two of you should investigate.
When you talk again outside of Skull Rock on Dazzle Beach, you will be prompted to give them a name, and that will add them to the valley like a normal villager. From here, you'll be able to enter Skull Rock and begin completing the quests you need to unlock Peter Pan.
