Stage Partners - Tips on Acting With a Co-Star
Act in Complement to your Duet Partner
When working as a duet on stage, the basic rule to remember is that you're NOT a solo act, and neither are you just another face in a larger set of actors on the scene. The tough part about a duet is that it combines elements of both the limelight of a solo act, AND requires the ability to interact with another actor that a scene with larger numbers demands. To this end, the most effective way to treat a duet is to complement your partner's moves, lines, and actions with your own. Think of it as if you were one pedal on a bike, and your partner the other. Work together as a team to get the scene going.
Don't be out to Steal the Show
One of the biggest problems for some duet acts is that one partner or the other may wind up being a prima donna who tries to hog all the attention and glory for him or herself. While this can work effectively for some scenes, there are quite a few cases where it ruins the scene altogether. Unless one character or the other is SUPPOSED to have an overpowering personality that overshadows the partner's character, try to avoid this. As an example of a case where a play can be ruined by this, consider a case where the villain's portrayal and presence overshadows that of the main protagonist. In the end, the audience winds up siding with the villain...
Work out Minor Details Beforehand with your Partner
This is very, very important. Small things can wind up ruining a big scene altogether. Remember that in acting, everything is used to convey the scene to the audience, from the volume and tone of voice of the actors, to small facial expressions, to subtle body motions, to the props and the placement of the actors on the stage. Work out every possible quirk with your partner beforehand to make sure that no small details cause a hitch in the scene when you actually get on the stage.
Practice both the Regular Lines and Ad Libbing
Lastly, in practice you should both work on the assumption that you MAY wind up forgetting your lines. So, instead of limiting your practice to the EXACT lines required by the scene, also practice ad libbing sessions where you both follow the spirit of the scene without sticking to the actual lines used in the dialogue. This way, if one of you suddenly develops a mental block, you won't be left flat footed and the scene won't grind to a halt.