Received at the beginning of Act 3.
Speak with Varric in his suite at the Hanged Man.
Varric and Anders are swapping tall tales when you arrive. Anders leaves, and you have a short chat with Varric. He talks about the power vacuum and issues in Lowtown, but there is no relationship effect.
Even if you told Anders to leave Kirkwall during Act 2 and he is neither at his clinic nor are you able to use him in your party (which would lead to the assumption that he has not yet returned for Act 3) he may still be there talking to Varric during this quest.