Because the play is a satire of marriage – how individuals get together in Victorian high society – there are several pairings that exist in the relationships of The Importance of Being Earnest. Algernon and Jack are friends; Jack and Gwendolen are lovers; Algernon and Cecily are lovers; Gwendolen and Cecily become friends; Miss Prism and Chasuble become lovers; Lane and Merriman are complementary servants for the two locales. Wilde – obsessed with symmetry – doesn’t just set up foils like your average playwright. He creates intricate patterns of language as the characters echo and oppose each other.
Could Wilde make Jack and Algernon any more similar? They’re both single men out to find the girl of their dreams. They both lead morally ambiguous double lives through the nonexistent characters of Ernest and Bunbury, respectively. And they both pretend their names are Ernest to get their girl. In fact, they even repeat each other’s lines:
Well, the only small satisfaction I have in the whole of this wretched business is that your friend Bunbury is quite exploded. You won't be able to run down to the country quite so often as you used to do, dear Algy. And a very good thing too.
Your brother is a little off colour, isn't he, dear Jack? You won't be able to disappear to London quite so frequently as your wicked custom was. And not a bad thing either.
As for your conduct towards Miss Cardew, I must say that your taking in a sweet, simple, innocent girl like that is quite inexcusable. To say nothing of the fact that she is my ward.
I can see no possible defence at all for your deceiving a brilliant, clever, thoroughly experienced young lady like Miss Fairfax. To say nothing of the fact that she is my cousin.
I wanted to be engaged to Gwendolen, that is all. I love her.
Well, I simply wanted to be engaged to Cecily. I adore her. (II.363-368)
This type of repetition shows that Jack and Algernon are practically identical in both character and predicament. They’ve both been caught lying. Both their gals are mad at them. And they both react the same way, repeating almost word-for-word what the other just said. In the end, the big punch line that they really are brothers isn’t that unexpected. With all their scheming, bickering, and making-up, they’ve been acting like siblings all along.
In the same way that Jack and Algernon are foils, Gwendolen and Cecily are too. They share the same basic character traits – two romantic girls out to catch and wed their respective Prince Charmings. They are both rich. They are both beautiful. And they’re both outrageously in love with the name Ernest. The only things that really differentiate the two women are Cecily’s relatively younger age and sharper wit.
In the same way that the two guys echo each other, Gwendolen and Cecily repeat each other’s lines, particularly in the twin scenes (in Act II) where the boys arrive and straighten out exactly who is engaged to whom. In a different way, Cecily supports Gwendolen by repeating her lines – much like cheerleaders will repeat their leader’s words in a chorus:
This dignified silence seems to produce an unpleasant effect.
A most distasteful one.
But we will not be the first to speak.
Mr. Worthing, I have something very particular to ask you. Much depends on your reply.
Gwendolen, your common sense is invaluable. Mr. Moncrieff, kindly answer me the following question. (III.9-14)
Gwendolen and Cecily's repetition here shows that they’re in the same situation. Having discovered their lovers are lying, they grow angry and want to interrogate them. And although Gwendolen and Cecily are not actually revealed to be sisters in the end, they do call each other sisters in a friendly way and become sisters-in-law when The Importance of Being Earnest comes to a close.