I've just completed the Pearlwood Bluff part of Sagani's quest "The Long Hunt". We had a conversation after finding the trace/memory of Persoq at the cliffs. At the end she asks "Anyway what about this Thaos character you're searching for? Seems like he was someone important to you. What do you remember about him?"
I have no idea who that is, I haven't gotten that far in the main story.