In the first two scenes of the play, both Antonio and Portia are portrayed as melancholy and depressed. In act 1, scene 1, Antonio admits that he is indeed depressed but does not know the reason for his sad mood. Antonio's friends attempt to discover the reason for his dreary attitude and suggest that he is either worried about his merchant ships at sea or has experienced a recent heartbreak. However, Antonio insists that there is no direct cause for his unhappiness and is unsure of why he feels so depressed.

Similarly, Portia is also in a depressed mood at the beginning of the play. In act 1, scene 2, Portia directly states the cause of her sadness by lamenting to Nerissa about her dismal romantic situation. Portia is unable to control who she will marry, which is determined by a lottery, involving three caskets, which was developed by her father on his deathbed. In addition to lacking control over her love life, she is not interested in any of her recent suitors and desires to marry Bassanio. While both Antonio and Portia are in melancholy moods, Portia knows and addresses the cause of her unhappiness while Antonio is unsure of why he is upset. The cause of Antonio's depression has been a highly debated subject and some people suggest that he is hopelessly in love with Bassanio, which explains why he is willing to risk his life to finance Bassanio's trip to Belmont.

In the first scene which features Antonio, the merchant is melancholy and depressed, but no one knows why.  Antonio admits only that his depression is not the result of love or business problems.

Similarly, when the audience first meets Portia, she is talking to her maid Nerissa and discussing her desire to honor her deceased father's wishes (in carrying out the casket plot) and her desire to choose whom she wants to marry.  She is conflicted just as Antonio is, but the audience knows the source of Portia's internal struggle.

The two characters do differ, though, early on in the play.  Antonio seems to be too rash in trusting others and in entering into risky business dealings.  In contrast, Portia is savvy and has the innate ability to "read" people.  She is also a much more optimistic person.