Tristan was a special guest in the Empire. The Eldoris people used him as a target to travel to the border of the Dawnstar and Empire. For Faerunians, after receiving the message, their representatives would arrive through a skill of Sea Snake. Vidalia had informed Damian that Sea Snake could make semi-alive water creatures that anyone could ride—they even flew in the air. It wasn't something they used often, suggesting a limited number of uses for this skill available to the King of Faerunia.
The message of their arrival today had already reached the border of the Dawnstar, currently under the rule of the Dragon Emperor. The Empire's important people were always present at the border. The Dragon Emperor himself was mostly stationed at the border city, but once in a while, when he wasn't there, a representative was sent by them too—if the subject of the meeting was important enough.
