Shylock is an unforgiving person. Although Antonio may have mocked him and cost his business to deteriorate, he should forgive Antonio but instead he seeks revenge.
“I’ll have my bond. Speak not against my bond. I have sworn an oath that I will have my bond. Thou calledst me dog before thou hadst a cause. But since I am a dog, beware my fangs. The duke shall grant me justice.—I do wonder, Thou naughty jailer, that thou art so fond To come abroad with him at his request.

Antonio gives up easily, instead of trying to convince Shylock to lift the forfeit and forgive him. He is also realistic, considering the consequences of Shylock lifting the forfeit. “I’ll follow him no more with bootless prayers. He seeks my life.” “The duke cannot deny the course of law. For the commodity that strangers have With us in Venice, if it be denied, Will much impeach the justice of his state, Since that the trade and profit of the city Consisteth of all nations.”

Antonio complains that he lost so much weight worrying about my losses that he hardly has a pound of flesh to spare for his creditor. There is dark humor used, to make the situation seem less serious.

Antonio calls Shylock a “bloody creditor” the diction here is useful as it not only shows Shylock as a cruel man, but also him cutting his meat off and getting bloody hands.

Shylock says that “Thou calledst me dog before thou hadst a cause. But since I am a dog, beware my fangs.” This is a metaphor to compare Shylock to a dog, which shows that since Antonio labeled him as a bad person, he would act that way.