In Shakespeare's "Twelfth Night", it is clearly evident that the fluctuation in attitude to the dual role and situation and tribulations imposed upon the character of Viola/Cesario ends up in a better understanding of both sexes , and thus, allows Viola to have a better understanding for orsino ">Orsino . Near the opening of the play, when Viola is adopting her male identity , she creates another self, like two masks and may decide to wear one or the other while swinging between the two identities in emotion and in character. She decides to take on this identity because she has more freedom in society in her Cesario mask, which is evident when she is readily accepted by Orsino, whereas, in her female identity she would not be. Thus, a customary role in society and to the outlooks of others is portrayed.
Orsino sees Cesario, as a young squire just starting out in the world, much like himself as a young, spry lad, so he has a tendency to be more willing to unload onto her with his troubles and sorrows, seeking a companion with which to share and to teach. Thus, Viola grows in her male disguise to get a better feeling for his inner self, not the self that he shows to the public, or would reveal and share with Viola in her true female self , but rather his secret self , as he believes he shares with a peer. So, she grows to love him. But, Orsino's motivation is actually not love for Viola, but rather he seems to be in love with love itself. His entire world is filled with love but he knows that there might be a turning point for him, like when he says:
If music be the food of love, play on; give me excess of it, that, surfeiting, the appetite may sicken, and so die. 1. (I,I,I-III)
This quote shows that he knows that he is so caught up in "love", that he hopes his appetite for love may simmer when he takes more than he can handle.
Near the end of the play, when all tricks and treacheries are revealed and all masks are lifted, Orsino "falls" in love with Viola. He first forgives her/him of her/his duty to him, the master; then says that she shall now be her master's mistress:
Your master quits you; and for your service done him, so much against the mettle of your sex, so far beneath your soft and tender breeding, and since you call'd me master for so long, here is my hand. You shall from this time be your master's mistress. (V,I,322-327)
This is sort of a switching love as he thought he was in love with Olivia in the beginning, but, he readily switches his love to Viola, as he feels he knows her personality well.
As for Viola, she declares her love for Orsino many times, as if by saying that she would love him if she were a lady. When Orsino first sends Cesario to act as a messenger and send Orsino's love to Olivia, Cesario proclaims:
I'll do my best to woo your lady;[aside]
yet, a barful strife! Whoe'er I woo,
myself would be his wife. (I,IV, 40-42)
This shows that Viola knows what a difficult situation that she is in, and that she might try to woo her out of loving Orsino, so that she might have him for herself; except there is a slight, unexpected twist of fate...
After Cesario leaves from Olivia's, she declares:
"What is your parentage?" "Above my fortunes, yet my state is well; I am a gentleman." I'll be sworn thou art. Thy tongue, thy face, thy limbs, and spirit, do give thee five-fold blazon. Not too fast: soft, soft! Unless the master were the man. How now! Even so quickly may one catch the plague? Methinks I feel this youth's per-fections with an invisible and subtle stealth to creep in at mine eyes. Well, let it be. What ho, Malvolio! (I,V, 289-298)
Olivia, is thinking back to her question to Cesario, and his response to it. Then she replies to Cesario's response, to herself, thinking about him. She agrees with his response, then goes over his many delightful features, and wonders how she so quickly has caught the plague of love for young Cesario.