Portia is a very intricate character as she has many different roles in the play. We first see Portia "weary" with life and then abusing the suitors that have come to Belmont to see if they want to take the risk of the caskets, the theory of which her father devised to see who would be Portia's husband, since he is dead. She doesn't covet to obey her fathers wishes and would like to marry Bassanio, whom her maid, Nerissa remembers to be a soldier and a gentleman, who, she believes, to be a perfect husband for Portia. Portia is highly critical of her suitors in Act 1 Scene 2. She describes them to her liking after Nerissa names then. The suitors she scathingly attacks are, Prince of Naples, Count Palentine, Monsieur Le Bon and Young Baron Falconbridge of England. Portia is then shown as highly intellectual in Act 4 Scene 1 where she intelligently and wittingly saves Antonio from death at the point of Shylock's, a Jew, knife. .
In The Merchant Of Venice, the following happens - this is a brief outline.
Bassanio wants to borrow money to court Portia as he has none, but, Antonio's money is tied up in his assets in the ships sent abroad, therefore Antonio borrows money off Shylock, three thousand ducats for three months. If it is not paid back, then Shylock may cut a pound of flesh on Antonio's chest. Launcelot, Shylock's servant leaves his service to work for Bassanio. Jessica, Shylock's daughter, elopes with Lorenzo.
The Prince of Morocco decides to choose the golden casket but "loses." Prince Arragon then chooses the silver casket but also "loses".
Is a rumour that one of Antonio's ships have sunk.
Bassanio chooses the lead casket an wins Portia's hand in marriage. They marry. Bassanio receives a letter off Antonio asking Bassanio to go to Venice to see him before Shylock kills him.
Portia and Nerissa pretend to go to a convent to pray for their husbands, but, they really go to the court room disguised as men to save Antonio's life.