Malvolio was a secondary character in the play. He was mainly there for comical relief and was very stuck-up. The other characters did not like him, to the point where a few (ex: Maria) locked him up and humiliated him.
This is Duke Orsino. This is who Viola went to work for and who she fell in love with. Orsino was in love with Olivia. Duke find himself falling later in the play for Viola who he believes was a boy. At the end the two end up together.