Who is Merteuil?

In “Quartet” written by Heiner Müller, how can audience know the time the characters act is after W.W.3 and the player is in the shelter? The play starts with blackout and sound speak first.

What is Valmont?

Who is he? Who is she? In “Quartet”, how Valmont came in the shelter? I took him as a person who only exists in Merteuil’s dream. So Valmont enters with sutle wind after she sleeps, which means Merteuil is all alone in the shelter(writer did not leave such scripts) ! Writers gives us an opportunity to use our humanity, imagination and freedom.