Preston
A man enslaved by gnolls on the island used by the gnolls to summon demons. He was held in a cell inside the mountain temple, presumably to be used as a sacrifice in the near future, until he was freed by the party.
From the temple atrium, taking three consecutive northwestern doors lead into a gaol with four cells, each containing two humanoids. Most of them were human, but one was an older-looking halfling and another was a dwarf. After one of the captives introduced herself as Celia, another captive called Preston recognized Vichthart as saving his life after the sinking of The Crested Eagle.
After the party killed Srir Silthallow, and Rrekkeh Stormcrawler escaped, the party freed these slaves and returned them to the mainland aboard Dancing in the Storm.