He keeps his gaze averted, his face turned just this way instead of that way so his expression is partial obscure. Of course hiding how he feels from the Just is a losing battle; Caspian X is a transparent person to those whoa re close to him, Edmund Pevensie is a tactical observer.

"I cannot say for sure, but I think..."

The Telmarine pauses. It's not his story to tell but he doesn't know the full extent of it anyway. Edmund, his friend's brother, deserves to know at least what Caspian thinks Peter was doing there. What he says perhaps absolves the blond from being a complete fool.

"I think he was visiting a friend," Caspian nods slightly. There's no need for words to imply said friend was not exactly present in person.