I recently encountered Plautis Carvain and company on the road one night.
According to UESP:
When approached and spoken to, he claims he is traveling to the wedding of an important Imperial personage and is carrying several rich gifts to give her.
After defeating the dragon of Mount Anthor, Plautis can be encountered traveling through the wilderness still in the company of his wife Salonia Carvain. When approached and spoken to, however, he claims that they had been robbed by bandits and their bodyguard eaten by a dragon and that they never made it to the wedding.
However, I wonder if they could be saved from this fate by having the Dovahkiin as a bodyguard. Obviously there is no dialogue for this, but I did manage to shadow them long enough to save them the trouble of a couple wolf packs, a thief, and a sabre cat. When I realized they had passed two road signs saying they were going in the wrong direction though, I gave up.
Has anyone tried following them around and protecting them long enough to see if they could eventually make it to their destination?