Malvolio seems stubborn and mad all the time which makes him look like a villain or the bad guy of the story. I believe Malvolio has to act a little mean sometimes, but that’s really just a coverup for some tragic events that happened in his life. Malvolio’s humor is very old and i personally don’t understand all of his jokes but i’m guessing in those times they were good. 

Notice how viciously Malvolio returns Feste’s “joke”. I believe he’s acting this way not only because Olivia seems to be letting Feste make fun of her (and him), but also out of jealousy. He’s already developed an affinity towards Olivia, and would rather not have her favor someone so un-worthwhile as this fool. Olivia begins by reproaching Malvolio, and explains why she let Feste make fun of her. She understands that Feste’s joking–and yet Malvolio takes his joke seriously.