I thought both actors did a good job in that scene, but I didn't like the scene because it felt gratuitous. They were just repeating stuff that had happened between them already; nothing new happened except that Amara is apparently shocked to learn that Dean has been plotting against her. Dean may feel some sort of weird thrall around her, but he *has* come after her with the intention of killing her before. She always seems so surprised when people she trusts have ulterior motives and act on those motives when they're not around her; you think she'd learn by now.