In Duke Orsino's palace, one of his pages, Valentine, enters, accompanied by Viola, disguised as a young eunuch, Cesario. By their conversation, we realize that after only three days, Cesario has already become a great favorite with the duke. In fact, Viola has won Orsino's confidence and favor so thoroughly that when "Cesario" enters, Orsino sends the others away so that he and Cesario might be alone. He asks Cesario to do him a very special, very personal favor. Cesario is to be the duke's messenger, his proxy, and carry notes of love from Orsino to Olivia. Cesario is to explain in detail the passion which Orsino has for Olivia and, in addition, Cesario is to enact Orsino's "woes." Furthermore, because Cesario himself is so beautifully handsome, Orsino believes that his avowals of love will be all the better received. His reasoning is that his love messages will entice the fair Olivia favorably because they will be presented in such a handsome package, as it were. Orsino also says that if Cesario is successful, he will be well rewarded; he will "live as freely as thy lord / To call his fortune thine."
Cesario is reluctant; in an aside, he reveals that "he" (Viola in disguise) has fallen in love with Orsino. Ironically, as Cesario, Viola will be doing some wooing for a man whom she would gladly have as a husband herself.
This scene shows us that Viola has been completely successful in carrying out her plan to become a member of Duke Orsino's household. Within a period of only three days she has completely captivated the duke, who has taken a fancy to her and is now not only employing her as his personal messenger, but he has also confided his innermost thoughts to her — that is, he has confided them to "Cesario."
At the opening of the scene, Valentine informs Cesario that he is likely to be advanced in the duke's service. This prompts Cesario to ask if the duke is sometimes "inconstant" in his favors. Viola is hoping that the duke will ultimately be constant to her — and yet she is also hoping that the duke will be inconstant in his affections for Olivia; it is not, however, until the last line of this scene that we discover that in these three days Viola has fallen in love with the duke. Part of the comic situation here involves the dramatic irony that Viola (in disguise) is forced to try to win Olivia for Duke Orsino when in reality, she would like to shed her disguise and be his wife herself.
At the end of the scene, Viola cries out, "Whoe'er I woo, myself would be his wife." This statement aligns Viola then with the other romantic lovers. She differs from them only by the fact that she is in constant touch with reality and can therefore evaluate her position.