Hello. You did not inform the play to which this question is referring, which makes it impossible for it to be answered accurately. However, I will try to help you in the best possible way.
The stage directions allow you to make inferences about the characters because they show how a character should act and what emotion he must pass in his movements and lines. This is because it is the stage directions that inform if the character is nervous, kind, evasive, violent, among other things. In this case, to infer something about Christopher and Lizzie, you must analyze what kind of emotion the stage directions display about them.
