[Quiet Man Cometh]

That came up a lot in War and Peace actually, how a character would use the formal "you" rather than the personal "thou" and that was Russian. ;)

It could reflect on how a person felt about the person they were talking to at the time. For instance, one character always adressed his beloved cousin as "thou" but after the potential marriage they both wanted became obvious it wouldn't happen, he started using "you" in a potential effort to detach himself.