Hmm. The relationship between Antonio and Shylock stretches beyond Act I, but if we limit ourselves to that act, we see the following:
Antonio needs Shylock, and, to a lesser degree, Shylock needs Antonio. There is therefore some degree of mutuality. They are also similar in that Antonio makes a point of saying he has not put all of his investments aboard one boat, but has spread the risk. Likewise, Shylock loans to many people. In these areas they are similar.
However, they are also similar in their dislike for one another, which is based in part on their religions, or at least, on the prejudices their time educates into them regarding their religions. Both also put on something of a false front when dealing with one another.
We know that Shylock drops this false front when...
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