Leliana likes you to reason with her and convince her Leliana is no longer a threat, at which point she leaves, reluctantly. --- The rivers will flow with the blood of those who shall oppose us. - Kane, suspected leader of the terrorist organization NOD
You get robes that improve blood magic if you kill the mage. You get warden commander armour if you kill Sophia. I actually noticed no approval or disapproval from any part of wardens keep, come to think of it.. I don't think your party really cares who you side with.