Much is said about cast chemistry. If I may be so bold, most of it is said by people who truly know little to nothing about the concept. They will watch a performance they enjoy, and give “cast chemistry” the credit, even if this is not the main reason the show was a success. Sometimes a show succeeds despite the fact that cast chemistry is in fact, quite lacking.
If that is possible, does that mean that oft talked about chemistry is not required?
Like many things in the performing arts, it varies with the circumstances. Two actors playing a happily married couple might benefit from chemistry more than two performers in a show who only exchange one or two lines of antagonistic dialogue together.
On the whole though, does it matter?
Many would say that if the actors on stage are good enough, it should not matter what kind of personal relationship they have with each other off stage. Indeed, colleagues of mine have argued that if you are really good, you should be able to convince an audience that your character is madly in love with the character of an actor you despise. This is for themost part true. (They say Vivian Vance and William Frawley, the Mertzes on “I Love Lucy” could not stand one another.) That is why, of course they call it acting.
Yet to me, no matter how good a performance may be between two people with no personal chemistry, there is always a transcendent quality to a performance between two people that do in fact have a healthy relationship backstage as well. This does not mean that one should strive to become the best friend of anyone they ever play a scene with. It does however mean that no matter how good you are, you will present a better performance to the audience’s subconscious, if you and your cast mates have established at least a cordial friendship. (Though the deeper the friendship and trust, the better off you will be, short of on-set romances which I have discouraged before.)
I maintain this is true even for performers playing antagonistic characters. Two people who hate each other in real life may be able to draw on some fraction of their real feelings in a Stanislovsky sort of way, and hence present some fireworks for a while. Fundamentally, however, it is all about trust and comfort. If you are comfortable with and trust your fellow performers in a scene, it will bring out the best in both of you. Most performers that despise each other as they perform will eventually just appear phony.
In sum, while warmth between you and your castmates is not a required element, I maintain that it is a very useful, and at times magical tool which adds that “little something extra” to a performance and show. The something may not be able to be quantified, but audiences, and you, will both feel an increased depth to your theatrical experience if is it there.