The pixies won't let you go free until you have completed some chores for them, and Ys Iala has one such task.

Requirements

This quest is available if you have completed the quest Il Mheg, the Faerie Kingdom.

Starting the Quest

Talk to Ys Iala in Il Mheg to begin the quest.

Obtain Fruit from Belltrees

Go northeast to the quest icons on the map. Check on the sparkling Belltree. Defeat the Soldier Crawler that attacks. Then go to the other quest icon on the map, check on the sparkling Belltree, and defeat the Soldier Crawler that attacks.

Deliver the Bellfruits to Ys Iala

Go southwest to where the orange arrow is pointing in the minimap and talk to Ys Iala to hand over the Bellfruit and complete the quest.

Next Main Scenario Quests

After you complete the quest, if you have also completed Oul Sigun's Plea and Sul Uin's Request, talk to Thancred to accept the next quest: Unto the Truth. There will be a cutscene.