Board Thread:General Discussion/@comment-71.0.110.185-20130112142431/@comment-5917342-20130118162529

It's part of Dark Brotherhood main quest line which cannot be changed by the player. The Farlkreath's sanctuary must be burned down as fate. After that, quest of Dark Brotherhood goes on. You may want to see what happens when you kill Astrid at first meet in the little dark house. Upon killing Astrid you receive the quest Destroy the Dark Brotherhood! in which you will kill everyone in the sanctuary with your own hands. Eventually you got 3000 golds as reward of destroying the Dark Brotherhood. If you only want the sanctuary itself be fine ignoring the members of Dark Brotherhood, you can choose to destroy the Dark Brotherhood.