How we cite our quotes: Act.Scene
Quote #1
Flam. So would I;
I would the common'st courtesan in Rome
Had been my mother, rather than thyself.
Nature is very pitiful to whores,
To give them but few children, yet those children
Plurality of fathers; they are sure
They shall not want. (1.2)
This is a totally ironic joke. Flamineo knows that the fathers of the children of prostitutes probably don't pay attention to their kids, or even know they exist. He's answering his mother's serious accusations and condemnations (she just said she wished she never gave birth to him) with scornful sass.
Quote #2
Isab. To dig that strumpet's eyes out; let her lie
Some twenty months a-dying; to cut off
Her nose and lips, pull out her rotten teeth;
Preserve her flesh like mummia, for trophies
Of my just anger! Hell, to my affliction,
Is mere snow-water. By your favour, sir;—
Brother, draw near, and my lord cardinal;—
Sir, let me borrow of you but one kiss;
Henceforth I'll never lie with you, by this,
This wedding-ring. (2.1)
Isabella's marriage has gone entirely off the rails. She (falsely) threatens Brachiano with divorce—but she doesn't mean it. (He's going to kill her, at any rate.) This is a crystal clear picture of exactly how disastrous their marriage has become.
Quote #3
Fran. Believe me, I am nothing but her grave;
And I shall keep her blessed memory
Longer than thousand epitaphs. (3.2)
Finally, someone who actually loves one of his relatives: Francisco is so genuinely moved by Isabella's death that it motivates his quest for revenge. His sibling-bond is one of the few familial relationships in the whole play that seems to mean anything permanent.