During Lunar Diplomacy, he is the navigator aboard the Lady Zay whom the player falsely accuses for mischarting the way to Lunar Isle. During Dream Mentor, he becomes the banker players must talk to in order to retrieve Cyrisus' items. Jack is a friend of Cyrisus, the NPC the player helps during Dream Mentor. After Dream Mentor, he will allow you to use the bank on Lunar Isle without needing a seal of passage equipped or in your inventory.