twelfth night: What do Orsino and Violado do to warrent their happiness at the end?

Orsinio sees the light of true affection. Orsino's affections shift by the end of the play; he drops his self-indulgent behavior, and develops affection for Viola. Viola works hard to be a friend and confidant to Orsinio even though she is supposed to be helping him woo Olivia.  For her part Viola  is in love with Orsino and finally pronounces her love for him (she can't for much of the play because she is supposed to be a boy).