Shortly before the beginning of Act three's drama, we see Isabella confronted by Angelo, where he proposes the question, "which had you rather, that the most just law now took your brothers life, or to redeem him give up your body to such sweet uncleanness as she that he hath stained?" Isabella had been literally placed in a life - death situation here, for if she were to give in to Angelo she would lose her integrity, and essentially her soul, but were she to defy him, her brother would be beheaded the next day. Isabella, as we have witnessed in past scenes, holds strong morals, and she indeed refuses to follow with Angelo's proposal. After this seemingly traumatic encounter, Isabella gives the audience a short soliloquy in which she highlights her situation, she has already decided in her head that her brother will die, "Then, Isabel, live chaste, and, brother, die."
Keeping in mind that Isabella has seemingly premeditated the outcome of her brother's sentence, the reader wonders why she is even informing him of Angelo's proposition. When she does speak to Claudio in act three, scene one, her explanation of the offer is slow and dramatic, she first establishes her moral position before she actually gets to mention the specifics, perhaps this shows that she does have faith in her brother's ideals. She starts off by over-emphasising how evil Angelo is, "There is a devilish mercy in the judge", maybe she hopes that Claudio would prefer is she didn't lose her chastity to a man so wicked in nature. From the point of her entry, we can sense a shift in the mood on the scene. There is a heightened feeling of suspense and anticipation as she continues to elude Claudio's questioning of the required act itself. During this time, Claudio is gradually getting frustrated, this frustration soon turns to brashness, "If I must die, I will encounter darkness as a bride and hug it in mine arms."
When Isabella finally yields to Claudio the term of his freedom, his initial reaction is of disgust, "Thou shalt not do't". Soon after, we as the audience gain an insight into the workings of Claudio's and essentially man's mind, for it is the human condition to be fearful of death. We can see that Isabella and Claudio differ quite significantly when it comes to moral grounds. Fornication in Claudio's mind is "the least" of the seven deadly sins, whereas Isabella clearly places her religious piety above all others. One gets the feeling that if Isabella had stated the proposition without delay, she would have not left Claudio in an excited and hasty state, and perhaps he would have given the proposition less thought. From his first reactions of boldness, we now see a weaker, almost pleading
Claudio, for when he speaks of death he gives a visceral description, one that comes from a man on the verge of an unknown journey into darkness and, "cold obstruction".
Claudio is seemingly on his knees now, "Sweet sister, let me live", this gives the reader the impression that Isabella is cold hearted and unmoving in her treatment of her brother.
Claudio, a desperate man, clinging on to the last straws of hope attempts to change Isabella's outlook on the situation, he makes it out to be that if she were to commit the sin with Angelo she would be saving her brothers life, and that end in itself would be sufficient enough to almost supersede the initial means. But Isabella continues to live up to her self righteous and hypocritical characteristics, for upon hearing her brother's plea she exhumes wrath, abusing him as a "beast", "faithless coward" and "dishonest wretch."
Isabella's willingness to sacrifice her brother's life to maintain her personal honour further separates her from her brother, for at this point; it is evident that it will be unlikely for the two to ever return to a normal relationship. Furthermore, it is interesting that amidst this power struggle, similarities in each other's character emerges, for while it may seem that they do not share the same views, in reality neither is willing to be a martyr for the other's beliefs. The Duke, in the disguise of a friar's habit, offers an end to the intense conflict that has taken course, with an alternate plan of events.
The relationships that characters possess are crucial to the overall theme of the play, for many, if not all of the questions raised in 'Measure for Measure' are in fact questions on human nature. In essence act three, scene one encompasses perhaps the central theme, a question of morals, love and religion. In their dialect we see Isabella give greater weight to religion over love when it comes to Claudio's life, perhaps the fact that Shakespeare rather abruptly ends the conversation suggests that this question in particular is one of great consequence and importance. For instead of giving us a clear answer, he leaves the problem open, and somewhat free to personal belief and opinion.