Thanks, David.

How about "But the whole time he was very pensive." Or instead of pensive, "reflective", or "pondering"? The word "thoughtful" carries with it a lot of kindness and sympathy which is not what Elvestad is going for in this scene. Also, "always" implies not only during this scene but during the stranger's whole life. The word-for-word translation, "the whole time" is exactly what he says and what he meant.