The character Ferdinand, the Duchess's brother, is notable for his exaggerated feelings and violent and abusive language. Some may feel that his characterisation is so extreme that it makes it difficult to take The Duchess of Malfi seriously, but he plays a central role in the dynamics of the play, and represents a personality-type which could just as easily exist today as in Webster's time.
Ferdinand: And women like the part, which, like the lamprey,
Hath ne'er a bone in't.
Duchess: Fie, sir!
I mean the tongue [Act 1, Scene ii]
This double-entendre shows Ferdinand's dark side. His persistent sexual innuendo aimed at his sister throughout the play shows that he has an abrasive temperament and unbalanced emotions. But discourteous and sickening as his behaviour is, he plays a pivotal role in the play.
Ferdinand is a younger repressed twin, and his wish for the death of The Duchess can be interpreted in many ways, his intentions towards his sister having been the source of much conjecture by critics. He obviously wants to dominate her and control her, but his wish appears somewhat futile, as she has been married before, and has thus gained her powerful status.
Ferdinand appears to lack the freedom of both of his siblings, as not only is his sister in a more powerful position than he is, but also his brother The Cardinal has the authority to practice politics on a much wider scale and can be present wherever he chooses. Ferdinand is torturously inhibited, and his brother's blasphemous affair and subsequent murder of his lover is painful to him, as is his brooding on his sister
In the shameful act of sin [Act 2, Scene v]
Incest was widely used as a theme in Elizabethan and Jacobean plays, Shakespeare's Hamlet (1600) and Beaumont and Fletcher's A King And No King (1611) being examples which Webster may have had in mind whilst writing The Duchess of Malfi (1614). The brother-sister incest theme was also take up later, spectacularly, by John Ford in 'Tis Pity She's a Whore (1633).
Webster has given Ferdinand the capacity for extreme love and hate. He is not married and appears to be without a mistress, which adds to his sense of alienation and inability to relate to women. Therefore he turns upon his sister who with her new-found freedom is an obvious target. Powerful women were considered unnatural and dangerous at the time, and Ferdinand is used as a mouthpiece for the public's judgements.
Ferdinand: There is a kind of honey-dew that's deadly:
'Twill poison your fame. [Act 1, Scene ii]
A modern day parallel to the marriage of The Duchess and Antonio might be a couple marrying with a large age gap, or a homosexual relationship. As with the relationship between the Duchess and Antonio these relationships are perfectly legal, but in the eyes of a narrow-minded and inflexible society are seen as deplorable.
In Webster's time most widows did not remarry, usually because they found themselves in a state of freedom and those left wealthy had the means to enjoy it. Webster brings his background in the legal profession to bear on the issues, showing the loopholes in the law of verbal contracts as an acceptable form of marriage.
Ferdinand is completely legally wrong to label his sister's children as 'bastards':
Ferdinand: For though our national law distinguish bastards [Act 4, Scene i]
And he exasperates her further by his doubt about their christening. Ferdinand constantly torments his sister with his madness. He is the antithesis of the cruel and coldly-calculating Cardinal, whose behaviour is less sinister than Ferdinand's which is motivated by his wild and fiery spirit. Ferdinand revels in the dark and in the play it is mentioned that he suffers with lycanthropia, a disease that makes the host believe he is a werewolf. The Duchess in contrast shuns the dark that Ferdinand operates in around her.
Bosola, whose character puts him in the category of the Renaissance dramatists' 'type', 'the malcontent', is in the service of Ferdinand, acting as a spy on The Duchess. He provides a great comedy element to the play, even though he is actually disgustingly unpleasant.
Bosola: She resembled an abortive hedgehog. [Act 2, Scene i]
He is the character who appeals to the working class in the audience who go to plays to see a blood-bath as entertainment. Webster also enjoys a pun on his name as 'Bos' can mean a protuberance on the body, or be slang for masterfulness.
Bosola can be likened to Feste in Shakespeare's Twelfth Night, in that he has the independence to roam among all strata of society and support all sides at once. But The Duchess makes a big mistake by trusting him, as he is the one who kills her on the order of Ferdinand.
With his dying breath Ferdinand comments on fate with an intriguing metaphor:
Ferdinand: Like diamonds we are cut with our own dust [Act 5, Scene v]
The diamond is a recurring image, and here echoes a speech made by the Duchess just before she is strangled.
Duchess: What would it pleasure me to have my throat cut
With diamonds? [Act 4, Scene ii]
Ferdinand may be acknowledging the downfall of his family by the dust in relation to the blood tie. His demise is a slide into isolation where every last light is extinguished.
It has often been pointed out that The Duchess of Malfi is a flawed play. For example Ferdinand reveals to Bosola a possible motive for wanting his sister to be murdered:
Ferdinand: To have gain'd an infinite mass of treasure by her death. [Act 5, Scene ii]
But this sounds unconvincing, as Malfi is little more than a poor fishing village. Moments such as these in the play have led it to be criticised for its plot, and it has other flaws. For example is it plausible that the Duchess could marry Antonio and have children in secret? Webster tends to neglect the importance of The Duchess' sons, and in Act 5 we see Delio apparently with a false heir.
But in spite of these flaws The Duchess of Malfi has lasted and remained popular, not just for its potent entertainment value and Webster's masterful use of language, but also for the insights it gives us into Jacobean society.