Orsino
Orsino is the play's presiding melancholic — his love for Olivia establishes the initial triangular problem, his intimacy with Cesario/Viola creates the play's real emotional centre, and his final redirection of love gives the comedy its resolution.
Appears In
Biography
Orsino opens the play with one of Shakespeare's most quoted lines — 'If music be the food of love, play on' — and then almost immediately orders the music stopped, which is a fair summary of his relationship to desire throughout the play: he wants what he wants intensely, and then wants something else. He is in love with Olivia, or more precisely with being in love with Olivia, and the play quietly distinguishes between these two things by making his actual conversations with Cesario far more emotionally alive than anything he says about the woman he claims to worship.
Orsino is not a fool, and the play does not treat him as one. He is intelligent, self-aware enough to know his own inconstancy, and capable of genuine warmth — particularly with Cesario/Viola, whose company he clearly values beyond the practical usefulness of a messenger. His famous speech on the difference between men's and women's love in Act II, Scene 4 — delivered to the woman he is unknowingly falling for — is both a self-portrait and an argument he is making without full knowledge of its irony.
His turn at the end of Act V — from rage at Cesario's apparent betrayal to the recognition that his love belongs to Viola rather than Olivia — happens quickly, perhaps too quickly for strict realism, but it works emotionally because the audience has watched the real relationship developing throughout the play. Orsino's love for Olivia was always more about the posture of loving; his feeling for Cesario, revealed as Viola, has been built scene by scene.
Motivation
Orsino is motivated by a genuine appetite for love and emotional intensity, though the play carefully suggests that his desire for Olivia is more about the romantic posture than the person, while his feeling for Cesario/Viola is the real thing he has been circling without knowing it.
Personality
Orsino is in love with love as much as with any specific person, and the play both indulges this quality — his lyrical speeches are genuinely beautiful — and gently anatomises it, showing a man whose emotional life is more vivid than his self-knowledge. His warmth and wit in conversation with Viola are more real than his sighing over Olivia, which is the play's quiet argument about where his feeling actually lives.