After defeating the assassins, Leliana will stop you from killing the leader, and you'll learn from him that the assassins were hired by somebody living in theĭenerim Market District. Soon after the conversation, you'll be attacked by a tough group of assassins on the world map (provided that Leliana is in your party).
Once you've gained enough approval with Leliana, the next time you visit the party camp she'll tell you about Marjolaine, a former mentor of hers who ended up betraying her in Orlais.
