Sharon was taken by surprise by the sudden news.

Rithrynn, in league with Sherpa, possibly mind controlled by the same curse or spirit that had affected Liaena earlier?
Liaena definitely seemed rattled by whatever it was that she had seen out in the city, and if she had seen Rithrynn, at the very homebase of Sherpa in any other character than murdering his crew, it was clear why she was worried!

Moving one arm behind Liaena, Sharon tried to calm the frantic girl as he thought about the recent news.

[i]"I could probably have made a mind control joke about there not being anything to control in the first place in the case of Rithrynn, but that would be highly inappropriate considering the circumstances."[/i]

"Rithrynn hasn't said anything or mentioned Sherpa since she came back. She has acted quite normal, or as normal as she can be." Sharon said as he looked at Liaena. Rithrynn, in a peaceful meeting with Sherpa could mean two things. 

First of all, Liaena's fears could be right, and she could in fact be possessed by a similar spirit as the one that had possessed Liaena back in Dalaran. In which case, they had a powerful evil force on their hands to deal with, right in their very base.
On the other hand, Rithrynn could have been playing a secret second game that none of them knew about. It seemed unlikely that she would support Sherpa, but then again, Sharon would never have expected Rithrynn to be the one to be toying with hidden plots and secrets. Those were games more in the domain of Liaena than the straightforward Night Elven Sentinel.

"If she really is possessed, we are going to have to be extremely careful... " Sharon concluded, his mind entering a brief contemplation.
"We should consult Marshall. If whatever's possessing her becomes suspicious that we could be onto it, Light only knows what it could do before we managed to contain it!"