Nathaniel sees Merrill's distress, her groping for comfort, and places a warm hand on her shoulder. The Wardens are continuing to kill their own. This is as bad as it gets.

"One more thing: we need to know where Clarel's Tevinter is."

He may be the lynchpin, if there is one. And there is no doubt at all that he's the force behind all of this, and has been since Erimond's capture.