You can talk with him from outside of the building, so you can avoid standing within the spawn. You must kill the spawn nevertheless afterwards since Markwin will abrupt the conversation before you can say anything.
You shouldn't end a conversation with 'bye' or 'farewell'. Markwin will answer "Go to hell! Burn!" and set you on fire resulting in an overall loss of 200 hitpoints.
Aside from a small group of outcasts, Markwin claims to be king of all minotaurs. He has never fully recovered from an encounter with a Dragon. His son's name is Ian.
Protected by a large labyrinth, the minotaurs in Mintwallin have been largely undisturbed in their underground community.