Monteverdi’s job, in writing music for the character Nero, was to capture the essence of a man who revels in his importance and responsibility as the emperor of Rome, but who has neither the wit nor the intelligence to be a truly great leader. His major weakness is that he succumbs far too easily to the whims of his emotions and is easily swayed, because of his indecisive and weak-willed nature, by the emotional manipulation of others, in this case, Poppea’s.
As was standard practice by Monteverdi and his contemporaries, the lead male role was sung by a castrati in the soprano part. In the case of Nero, this assignment of the soprano part to the lead male, happens to be particularly fitting. Nero’s flighty and whimsical attitude toward his relationships and his vain and childish attitude toward his role as emperor are well represented by the perpetually immature voice and mentality of the castrati singer. Just like Nero’s conception of reality, the tessitura of his part is way up in the clouds.
Another way in which Monteverdi demonstrates Nero’s weak will and dependence on the input of others to move him into action is that he never sings an aria alone and of his own volition, but instead sings only dialogues with others. This aspect of his part also demonstrates his lack of regard for his personal relationships either with other characters, such as his wife, Octavia, or his court advisor, Seneca, or with the people whom he governs whose opinion of him he seems to have no concern for. Because of this use of duets, we never see him privately tormented by the ruthless decision he has made to divorce his wife and marry his mistress. He cares nothing for his reputation or moral responsibility as emperor, but only for his lustful and vain desire for Poppea and their little game.
His inability to think for himself is further illustrated by his musical relationship with Poppea. Monteverdi helps to show her ability to manipulate Nero by creating instances in which she forces Nero to change to a different key. She vocally sets him up so he is forced to cadence on her chosen melodic goal. In “Deh, non dire di partir,” for example, she forces him by way of choral manipulation to cadence on A minor, away from the major keys he was using in an attempt to hold himself back from her seductive power (even though he knows he can’t resist it). She also causes him to part from his consonant and major tonality, and give in to the chromatic and seductive style of singing which she uses to seduce him. Thus we see the highly effective manipulative side of Poppea who, through using this capability, becomes the only real winner by the end of the opera when she successfully steals the crown from Octavia and whips Nero into a loyal and obedient puppy dog.
Nero’s flighty and whimsical personality is also implied by his disjunct melodic lines.
Although generally consonant, these lines seem to fly around with little direction and tend to end
on relatively weak cadences, especially when he becomes emotionally charged as in the debate he
has with Seneca over whether or not he should do away with Octavia in order to marry Poppea.