More of Xzar and Montharon after Nashkel mines

Hi

I find Montharon and especially Xzar to be very entertaining characters and I would love to hear and read more of their dialogue but after I finish the Nashkel mines they don't seem to react at all. What was their agenda there in the first place? Is there a special quest I can trigger that will catch their interest or anything else I can do to trigger them to be more active conversation-wise?

Thanks in advance