Tharstan is a Nord historian who can be found in the Skaal Village studying the Skaal. Until the quest The Fate of the Skaal has been completed, he is one of the villagers building a temple around the Wind Stone.
"I heard from Deor how you went in search of Baldor. That was very brave, and in fact, that's just the kind of courage I'm looking for."
- Let me guess, you need me to do something dangerous: "Quite right! Quite right! This, however, is paying work. Allow me to explain."
- I helped a man in need, that's all: "Modest as well as brave. Most admirable! I can see why the Skaal think highly of you. Yes I think you're just the adventurous sort I need. I have a job offer for you."
As a scholar of history, I've always found Solstheim to be most intriguing. I've made many forays into the ancient ruins that cover the island. I've come to know those ruins so well, I could draw you a map from memory. That's why I noticed the new passage the moment I laid eyes on it."
A new passage to what?: "An old tomb, I think. It must have been opened by an earthquake that accompanied one of the Red Mountain's eruptions. I'd love to have a closer look, but those old ruins can be dangerous and I'm no adventurer. I'll pay you to watch my back down there. I'll be heading back there soon. If you're interested, meet me at the ruins and we'll see what we can find. Now I'm off to pack for the expedition!"
After the conversation is over, the quest will begin and Tharstan will head off to Vahlok's Tomb. Once the Vahlok's Tomb has been explored and the Dragon Priest Vahlok defeated, he offers additional insight into the origins and details of the Nordic ruin and how it relates to Vahlok and Miraak:
How amazing! A real Dragon Priest! In all my years as a historian, I never though I'd see anything like that. I suppose that was Vahlok. He must have had this entire place built for him so that he could maintain his vigil, even beyond death.
He must have been someone important: "Indeed. I knew that the Dragon Priests were thought to have been powerful men of great will, but I had no idea. Well, I suppose I've seen everything I came for, and you kept up your end of the bargain. I promised payment and here it is."
- Why all the traps and puzzles?: "A good question. Partly to keep unwanted intruders away, I suppose. they might also have been meant as tests, to ensure that only the truly worthy can reach the main burial chamber. Who can say, really? The motives of the Dragon Priests are as inscrutable as those of the Dragons they worshipped."
- What have you learned about this place?: "This is clearly a tomb, if a rather elaborate one. I would guess it was built for a Dragon Priest who achieved great fame in his time. It seems he was held in high regard by both men and dragons, because he defeated a traitor named Miraak. Perhaps Miraak was also a Dragon Priest, probably a contemporary of this guardian. He must have turned against his own order. After his defeat, Miraak was banished to Solstheim and the guardian was made his jailer."
- Do you think this place has any connection with the Skaal?: "I've been thinking about that, and I believe it does. I believe it was the ancient ancestors of the Skaal who built this tomb for their master, the Dragon Priest they called the guardian. In all likelihood, these people were ancient Nords who came with the Dragon Priests to live here on Solstheim. Separated from their people on the mainland, that developed a distinct culture that became the Skaal we know today. Of course this is all just theory and conjecture. It is likely we will never know the truth."
- Tharstan will stay behind, purportedly to study the Word Wall, where he will mention "There's enough here for entire volumes!"