He makes the effort not to look like he's watching, particularly as closely as he is, but his gaze strays back to Mordred no matter where else he casts it.
(He had always known that Mordred had a friend, and brothers who loved him, all that long time ago, but he had never connected that to Mordred's humanity, his capacity to be gentle and careful and kind. It's unexpected, and he's ashamed that it's unexpected, but he's also touched, and that feeling is strong enough almost to eclipse the shame. He wants, suddenly, to know more of this, to see this part of Mordred, and he feels it like a pang, with a longing he hasn't felt since Percy.)