With King Robb's coronation approaching, visitors begin to arrive in King's Landing from around Westeros. Robb and Margaery are particularly interested in seeing where Dorne stands, and who they send to the capital.
Princess Arianne represents Dorne, introducing herself to Robb at last
Robb has been very interested in meeting Arianne Martell so he could thank her in person for sending her cousin Tyene Sand to King's Landing to help Sansa sneak out before he took the city from Stannis. When she comes to King's Landing for the coronation on Dorne's behalf, Robb is happy to greet her, and Arianne is happy to become better acquainted with both Robb and Margaery.
Oberyn comes, and Robb and Margaery help his paramour Ellaria Sand cum
The Red Viper is an interesting sort, but Robb is admittedly more interested in his beautiful paramour Ellaria. While Oberyn visits the Street of Silk on his own, he asks the king and queen to keep his lover company. Robb and Margaery are happy to oblige.
The Red Viper is Dorne's representative, and he brings some of the Sand Snakes
Robb has already had the pleasure of meeting Tyene Sand, and when more than one of Oberyn's bastard daughters come with him to King's Landing, Robb is quick to welcome them. The Sand Snakes might not be in a position to have any say over what Dorne does, but Robb and his queen still find them more than worthy of some hospitality in the royal bedchamber.