Lorenzo is a quintessential heroic figure, embodying the traits of a dashing and chivalrous young knight. However, he is not above manipulating others to achieve his goals. This is evident in his pivotal role in convincing Don Abbondio to marry him and Lucia against the priest’s initial resistance. Lorenzo is a fiery and passionate young man, characterized by his deep love for Lucia and his willingness to engage in political unrest in Milan. His enthusiasm for life includes a fondness for alcohol and several narrow escapes from the law. Despite these flaws, Lorenzo’s resilience and determination shine through. He bravely returns to a plague-stricken Milan to find Lucia and even overcomes the illness himself. Although not inherently cruel, he ultimately forgives those who have caused him and his betrothed significant distress. His journey is marked by separation from Lucia due to the machinations of the villainous Don Rodrigo, and he is forced to leave Milan after participating in a famine riot. After a year, he reunites with Lucia, who has fallen ill with the plague, but she recovers, and they finally marry.

Lucia is the embodiment of the medieval feminine ideal, possessing not only physical beauty but also a radiant innocence and virtue, as noted by "The Unnamed." Her strong religious faith leads her to make a vow to become a nun if she is rescued from her captors, placing her spiritual commitments above her personal desires. However, Fra Cristoforo advises her that her betrothal vow to Lorenzo takes precedence, allowing Don Abbondio to eventually marry the couple. Lucia is the object of Don Rodrigo’s unwanted advances, leading to her kidnapping by his henchmen. Despite the tumultuous events, including her temporary separation from Lorenzo and subsequent illness, her unwavering faith and purity are guiding lights throughout her trials.

Don Rodrigo is an arrogant nobleman whose snobbishness is emblematic of his class. He views Lucia as a mere object to be possessed, driven by a bet to seduce her. His pursuit is relentless, and he exercises his power cruelly, ordering Don Abbondio not to marry Lucia and Lorenzo. However, Rodrigo's looming threat dissipates as he succumbs to the plague during his search for Lucia, marking the end of his influence over their lives.

Fra Cristoforo is a saintly Capuchin monk whose virtue stands in stark contrast to the malevolence of Don Rodrigo. He boldly defies Rodrigo's wrath by offering sanctuary to Lucia. His commitment to helping others extends to returning to Milan amidst the plague, where his efforts include persuading Lorenzo to forgive the dying Rodrigo, showcasing his deep compassion and ability to inspire mercy in others.

Don Abbondio is a cowardly parish priest who initially succumbs to Rodrigo's threats, refusing to marry Lorenzo and Lucia. Despite his timidity, he is fundamentally good-hearted, risking his life to ring the church bells and prevent Lucia's abduction. Ultimately, he aids in uniting the couple at the novel’s conclusion, serving as the agent of their long-awaited marriage.

"The Unnamed" is a complex character, a powerful outlaw nobleman more influential than Don Rodrigo, yet initially complicit in his schemes. His men kidnap Lucia, but her purity and innocence provoke a profound change in him, leading to his repentance from a life of tyranny. He becomes instrumental in ensuring Lucia's safety, assisting her escape to a noblewoman's protective household.

Cardinal Federigo is an influential and well-connected clergyman, distinguished by his empathy and moral fortitude. He takes an active role in safeguarding Lucia, providing her with a refuge out of Rodrigo's reach and thereby playing a crucial part in her eventual freedom and safety.

This nun is a headstrong aristocratic woman who finds herself coerced into a life within the convent. Her lack of moral firmness is exposed when "The Unnamed" successfully pressures her into expelling Lucia from sanctuary, highlighting the nun's vulnerability to external manipulation.