This page explains how to complete the level 82 Endwalker quest "Personae non Gratae".
This quest is available if you have completed the quest The Last Bastion.
Starting the Quest
Talk to Jullus in Garlemald to begin the quest.
Gather Information in Tertium
Talk to Caeso, who is near the Aetheryte.
Go south from the Aetheryte and talk to Octavia.
Go northwest from Octavia and talk to Sabinianus.
Go north from Sabinianus and talk to Marcellinus.
Go east from Marcellinus and check on the sparkling Magitek Radio.
Speak with Alphinaud
Go northeast into the middle train car and talk to Alphinaud.
Go north to the quest icon and check on Flavius.
Speak with Alphinaud Again
Go south to the quest icon and talk to Alphinaud.
Speak with Jullus
Exit the train and go to the quest icon on the map. Talk to Jullus to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, you will need to be at least level 83 to proceed to the next quest. After you reach level 83, talk to Jullus to accept the next quest: His Park Materials.