When the two actors get down stage Antigone would stay stage right and Ismene would walk more into stage left again showing a difference in opinion and relationship. Antigone would stand with her weight on her back leg with her arms crossed and her focus straight forward on the audience, whilst Ismene would have her front leg bent with her back leg turned to the left as well and she would be looking to the ground and have her shoulders turned away from Antigone as well showing disagreement. To the audience this should communicate that Antigone has the stronger status and is not afraid of what she is doing where as Ismene is afraid and is scared to show as much power as her sister. Ismene is looking to the ground showing she is alone, scared, upset even and she is not making any eye contact unlike Antigone who is focusing on the audience and making sure that they know she isn’t scared and she is focused both on them and what she is going to do.
Before Antigone's first line she would have to look at Ismene to get the audience to look at Ismene with her and to show that Antigone isn’t that harsh as a person, so Antigone would look at Ismene before sending her line to open the scene, to show emotion and then she’d say the line sympathetically to gain Ismene’s trust and try to persuade Ismene to come with her. Antigone would turn, look at Ismene and then say “Sister Ismene, dear sister Ismene” I'd have Antigone pause for a while after she says “Sister Ismene...” I'd have her pause begin to walk straight towards Ismene with her arms out to the side trying to attract her attention. I would have her pause because she is thinking and trying to see if Ismene will look at her; when Ismene doesn’t, Antigone ends the pause and then walks over to catch her attention again, but Ismene for a second time would ignore her so then Antigone would say “…Dear sister Ismene” when she says this line she’d put her hand on Ismene’s shoulder to show she cares, but really I think she is using reverse psychology.
Ismene would then drop her shoulder so Antigone's hand falls off Ismene's shoulder, and then Ismene would turn away from Antigone even more and drop down a level in the way she is standing, so as a director I'd have Ismene arch her back a little and place her hands on her knees showing very low status towards Antigone's superior status. Ismene would then deliver her line quietly but loud enough for people to hear her, but the line would be said much softer than Antigone's.
“What's this, black news I see already” Ismene would deliver this line to start with softly on the “What's this…” then when she says “…black news I see already” she would more or less force this line down Antigone's throat, to show she does have status, she has some but not a lot, not as much as Antigone. With this line said Antigone would step back in shock from Ismene speaking up for herself and Ismene would have gained her up right stance with her hands on her sides showing conflict and status. The audience should find out that Ismene is not a quiet little girl we all expected her to be, but in fact she is trying to gain back her status and she’d show this by moving into Antigone's space and challenging her for status.
Antigone would now be a little shocked and to show this shed step back as Ismene turns with her left leg forward Antigone would put her left leg behind her so as Ismene turns Antigone would follow her with the same legs turning at the same time, this would be a synchronised piece of movement which should sow the audience that these actors have thought about where and when they are moving as actors and it should show the audience that these two characters know each other very well.
Antigone needs to strike back and she does with her next line. Antigone has just be questioned by Ismene and Antigone needs to hit back so she tells Ismene that now is the time to prove herself. Antigone's line is “…now is your time to show weather or not you are worthy of your high blood” Antigone is challenging Ismene and putting her in a difficult situation as Ismene doesn’t know weather to go with Antigone or to stay. We know this line is exaggerated. She exaggerates this line to get Ismene attention and to inform Ismene that she is not messing around but in fact she is being serious. She would show this by moving into Ismene's space and challenging her, but as soon as Antigone thinks she has the upper hand, Ismene comes out with her last line and pushes Antigone away showing she has had enough and wants to know where she stands. She does this by pushing away Antigone's hand and projects her voice so it goes through Antigone and straight to the back of the audience. “What more can I do, or undo, to help you?” Ismene would say this starting off slow getting faster getting louder, invading Antigone's space and focusing on her face continuously walking into her space pushing Antigone backwards continuously.
Throughout this scene it’s all about not knowing what to do between each character and not knowing how the other feels, so these two characters are always going to be pushing for higher status and pushing for more space, so this is how I'd direct this particular scene.