Just like figuring out any title for an essay or other piece of writing, the best way to figure out titles for the acts in Twelfth Night is to zero in on what's important about the act. Ask yourself, why is this act important? What role or function is it serving? One way to answer those types of self-directed questions is by figuring out the important themes of the play at large and in each individual act. A theme is a central idea "that unifies and controls an entire literary work" (Dr. Wheeler, "Literary Terms and Definitions: T"). A theme can be an insight or even just a simple concept. Dr. Wheeler gives us the examples of "progress," "order and duty," or even "jealousy." We can use Act 2 as an example.
In Act 2, disguise and deception are frequently discussed, plus consequences of disguise and deception are revealed, making disguise or deception a strong underlying theme. We first see consequences of disguise referred to when Olivia sends Malvolio after Viola as Cesario with a ring. It is in this instant that Viola realizes Olivia has fallen in love with her and meditates on the dangers of disguise or deception, as we see in her lines, "Disguise, I see, thou art a wickedness, / Wherein the pregnant enemy does much" (II.ii.26-27). The theme of disguise or deception is even carried out in Maria's idea, along with Sir Toby and Sir Andrew, to trick Malvolio into believing Olivia is in love with him as a means of both proving Malvolio to be a fool while avenging themselves for his uptight, moral, judge mental character, which contrasts greatly with their own wild, bawdy, wasteful behavior.
Hence, since disguise and deception is such a dominant theme, one could create a title for the act referring to the consequences of disguise:
- The Consequences of Disguise
Or one could even take some of Cesario's important words and use them in a title:
- Disguise: "Thou Art a Wickedness"