I loved how last week Arthur did admit Merlin was the only one he could really trust, but damn, it WOULD be fun to see Agravaine try to undermine that. Although it's so nice to see that trust and how matter of fact they are about it, so I wouldn't want anything to jeopardize that. But yes, ideally once Arthur finds out about Agravaine's treachery, he'll turn to Merlin and be all "Sorry, I should've trusted you about this. You're always right anyway." and stuff ;)