Here me out, when we spawn in the tavern's all we see is the girls at behind the counter, the mysterious pirate at the back, and Duke. So I am thinking, there should be other pirates/other people in the taverns, but not just the same people, but different pirates (like each tavern will have at least six to seven NPC, different from each other at other taverns around the seas of Sea of Thieves). For instance:
THE WILDS: - These are ruthless and aggressive NPCs. This is where you will see most of your fighting, rough-housing, and drunkard pirates. They tend to want to pick a fight with you, REGARDLESS of what you do.
THE ANCIENT ISLES: - These NPCs' are your more sane and simple pirates. You can interact with them without any hassle and they tend to dance, have fun and talk to one another, including you. They are more of those pirates were they are not to aggressive, but will sometimes get a little tough here and there.
THE SHORES OF PLENTY: - This is where your rich and classy pirates are located. They speak class and are condescending. They will also talk smack about the pirates in the Wilds, and talk more mannerly about those in the Ancient Isles.
DEVIL's ROAR: - Straightforward, The Wilds' pirates but 2x worst.
