When the Dragonborn reaches Karthwasten, Ainethach is arguing with Silver-Blood mercenaries about Sanuarach Mine. The mercenaries want him to sell it to them in repayment for their help in clearing the Forsworn rebels who had captured it.
The Dragonborn has the option to choose to help him keep his mine, by either convincing Atar and his mercenaries to leave, or by simply killing them so they are no longer an issue. It is also possible to side with Atar instead, and convince Ainethach to sell his mine. Regardless of which side is chosen, the Dragonborn will receive a leveled amount of .
During the quest "Recipe for Disaster," if the Dragonborn kills the helpers of the cook, Voada and Rondach, in Understone Keep, Ainethach may send hired thugs to teach them a lesson. This is because the Creation Kit lists them as his children. However, there is no in-game dialogue or text that refers to their relation.
Ainethach is a marriage candidate. As with all possible spouses, he makes a daily profit of 100 that does not have to be collected every day. He will hold onto the amount as it increases until it is asked for by the Dragonborn.
Ainethach "I want you sellswords out of my mine."
Atar "Watch your tongue, native. We'll leave when we're sure there are no Forsworn here."
Ainethach "Oh, and when would that be, I wonder? When I sell my land to the Silver-Bloods?"
Atar "The Silver-Bloods have made you a very generous offer for this pile of dirt. I suggest you take it."
- "I'm one of the few native sons of the Reach that owns land. It doesn't make me very popular."
- "The Forsworn think I'm working for the Nords. The Nords think I'm working for the Forsworn!"
- "They already own half of The Reach, and they won't stop until they own all of it!"
- "The Forsworn attack the mine, and suddenly all these sellswords show up to 'help'."