Greston, who lives in the Stico Cave, asked you for a favor. He wants you to go to his mother Faoda, who is in Covelly Village, and tell her he is very sorry. He will begrudgingly give you the compass that goes with A Meeting With A Pirate/'Find My Compass' quest for Virgul the pirate so he can leave Stico Bay. You could also kill Greston and get the compass that way.