Nathaniel looks surprised, then there's a flash of guilt over his face because Anders is talking about the Wardens failing him at a time when Nathaniel was a Warden. He's talking about Nathaniel failing him. Not specifically, but it's in there. Then there's a flash of irritation.

"Nobody made you stay in Kirkwall so long, Anders. And if I hadn't talked you into coming back, you would still be dodging the Wardens altogether. What did you expect?"