Primo Antonius is a well-born Imperial guest in the Whodunit? quest. He claims that his father owns more property than the East Empire Trading Company. He isn't overly fond of the other guests but doesn't hate them, he is attracted to Dovesi Dran.
A client has arranged a party in order to kill off some enemies with the Dark Brotherhood's help. The goal is to kill all the guests, and a bonus is given if nobody witnesses any murder. To make it easier to kill him the Hero can tell Primo that Dovesi Dran is waiting upstairs for him, where he can then be killed away from prying eyes.