Ehm, Varric doesn't want anything to do with Anders anymore. Don't you think it's kind of unfair to blame him for what his friend did, especially since he cut his ties with the guy after he blew up the Chantry? Cassandra had every right to interrogate Varric, but her technique sucked. You can't go all bad cop on him and expect him to respond favorably.
Im not blaming him for what his friend did, i just think he got a bit one note when it came to Cassandras treatment of him. When shes not around hes actually quite good at accepting his responsibility for part of what has happened. Scatch that, because he goes too far and completely blames himself for everything.
I like Varric a lot, but he seriously needed a more balanced approach in his interactions with Cassandra. Its a shame because when she brings up Bianca and he brings up her romantic life they make a good common ground. Just whenever it comes to Cassandra, its all "you was nasteee to meeeee! QQ"
Ironic really since all Cassandra had done was have him possibly knocked out, thrown into a chair and then stabbed a book betwee his legs.
Hardly the realms of waterboarding or pulling fingernails.