Duke Orsino is the duke of the town Illyria mentioned in the play. Of all the characters in the play, his social rank is highest. He begins the play with a declaration that if music is the food of love, play on.
It shows that he is moody. He represents the tradition of courtly love of Elizabethan age perfectly. He is a good ruler because a sea captain describes him as “a noble duke, in nature as in name.”
Olivia does not return his love but at the same time, she acknowledges his goodness. She says that “your lord does know my mind, I cannot love him. Yet I suppose him virtuous, know him noble, of great estate, of fresh and stainless youth; in voices well divulged, free, learn’d. and valliant, and in dimension, and the shape of nature, a gracious person.”
It is a complete description of Orsino’s character. As a duke, he is extremely cultured. He loves music and, in many scenes, he is surrounded by musicians and singers. He enjoys arts.
Whenever he speaks on elevated matters such as love, his language is literary. It tells us about his knowledge. At the same time, it also tells us of his self-love because it seems like he enjoys listening to himself.
The love which he expresses is so ideal and affected that it looks unreal to us in our age. His love for Olivia is sentimental and proves unreal in the end but his affection for Cesario/Viola is real.
In a courtly fashion, he forces his love to Olivia in a persistent manner with a false hope that she will ever accept it. He starts enjoying the whole process of such an unfulfillment.
Orsino’s mind is immature. The clown in the play describes it as “for thy mind is very opal.” He is very moody while dealing with things in day to day life. His aggressive manliness has been turned upside down to reveal how comic it actually is.
Apart from these weaknesses, others have a good opinion of him. He shows maturity when he describes the bravery of Antonio even though he used to be his enemy. He corrects his pretention when he accepts his affected declaration of love for Olivia and takes Viola as his wife and accepts her love.