"Twelfth Night" is one of Shakespeare most perfect comedies. It is a perfect blend of romance and comedy. Although the play has a main plot and a subplot, the structure of the play has been skillfully handled in order to give importance to both.
Act I serves as the exposition as it introduces most of the characters of the main plot. Viola's disguise as Cesario also
initiates the love triangle, for Viola falls in love with the Duke at first sight, while the Duke is in love with Olivia. Olivia is initially attracted to, then eventually falls in love with Cesario/Viola. Act II presents the rapid rising action of the main plot with Sebastian Viola's twin brother traveling to Duke Orsino's court. The audience now waits for the complications that will arise because Viola and Sebastian look alike. Olivia declares her love for Cesario/Viola indirectly through a ring sent to her.
The action is also focused on the subplot. Sin Toby Belch, Maria, and the other minor characters are determined to teach the conceited Malvolio a lesson. This is the introduction to the subplot, which rapidly rises as Malvolio reads the letter and is willing to follow the instructions of the letter.
Olivia, now passionately in love with Cesario/Viola is willing to tell Cesario/Viola about it. The opportunity arises when Viola visits her again on behalf of the Duke. Olivia's open declaration of love for Cesario/Viola marks the climax of the plot. Following the declaration, matters will slowly begin to move in the direction of resolving the complications arising as a result of Viola's disguise.
The first of these situations is when Viola is mistaken for Sebastian by Antonio. The audience, who waited for such complications to arise, can now enjoy the humor of the situation.
The falling action...