The first page of the novel introduces the reader to Monsieur Myriel, the Bishop of D—. Before meeting Jean Valjean, the Bishop foreshadows the stolen silver and the grace that he shows such thievery with personification and situational irony:
That evening, before he went to bed, he said again, “Let us never fear robbers nor murderers. Those are dangers from without, petty dangers. Let us fear ourselves. Prejudices are the real robbers; vices are the real murderers. The great dangers lie within ourselves. What matters is what threatens our head or our purse! Let us think only of that which threatens our soul.”
The Bishop tells his sister to never fear robbers, only chapters before Jean Valjean comes into the Bishop's home and takes advantage of his kindness. The irony lies not only in the fact that Jean Valjean robs the Bishop of his riches, but also in the fact that the Bishop's lack of prejudice allows Jean Valjean to keep the stolen riches. However, the Bishop's unending forgiveness also allows Jean Valjean to understand his wrong and atone for his sin.
The Bishop also uses personification to compare prejudices to robbers and vices to murderers, explaining that the greatest sins and evils lie within ourselves. The most precious treasures are people's minds, so tainting them with prejudices and vices is a form of treachery against ourselves. Holding prejudices against certain people robs oneself of a fulfilled life. Giving into vices is akin to murdering one's most fulfilled self. This outlook demonstrates the Bishop's selflessness, as well as his devotion to people over riches.
When a cruel man throws snow onto Fantine's bare shoulders, she attacks and curses him. Javert arrests Fantine and brings her to the police station, where spectators ironically revel in her misery:
The cloud of spectators followed, jesting, in a paroxysm of delight. Supreme misery an occasion for obscenity. On arriving at the police station, which was a low room, warmed by a stove, with a glazed and grated door opening on the street, and guarded by a detachment, Javert opened the door, entered with Fantine, and shut the door behind him, to the great disappointment of the curious, who raised themselves on tiptoe, and craned their necks in front of the thick glass of the stationhouse, in their effort to see. Curiosity is a sort of gluttony. To see is to devour.
The people of Montreuil-sur-mer surround the spectacle of Fantine's attack and arrest, drawn in by the "supreme misery" of it all. Such pain inspires a "paroxysm of delight" in the crowd, highlighting the situational irony of their interest—what's ironic, of course, is that these people feed on misery as a way of dulling the pangs of their own hunger. In other words, they delight in suffering even as they themselves suffer.
After Fantine gives her daughter Cosette to the Thenardiers, she returns to Montreuil-sur-mer to make a living in the new manufacturing town. The women's workroom, however, is a place full of ironically curious people:
There is no one for spying on people’s actions like those who are not concerned in them. […] They will bribe errand-porters, they will make the drivers of hackney-coaches and lackeys tipsy, buy a waiting-maid, suborn a porter. Why? For no reason. A pure passion for seeing, knowing, and penetrating into things. A pure itch for talking. And often these secrets once known, these mysteries made public, these enigmas illuminated by the light of day, bring on catastrophes, duels, failures, the ruin of families, and broken lives, to the great joy of those who have “found out everything,” without any interest in the matter, and by pure instinct. A sad thing.
The story uses situational irony to illustrate that the most effective way to spy on people is to have it done by someone whose business it is most definitely not. People, especially the women in the workroom and Madame Victurnien, are nosy and fascinated by other people’s secrets and mysteries. They offer a sort of entertainment and liveliness to an otherwise monotonous environment, even though the uncovered secrets often result in pain and desolation. More irony exists in the narrator's point that the people who pry feel unbridled joy when they have successfully “found out everything” and thus broken someone’s life. In the world of Montreuil-sur-mer, curiosity is akin heartlessness.
When Monsieur Leblanc—Jean Valjean—goes to the Gorbeau building and walks right into a trap, Jondrette reveals that he is the inn-keeper Thenardier. Marius, who is spying from the next room, uncovers the ironic secret about the man who saved his father's life at the Battle of Waterloo:
This man was that Thénardier, that innkeeper of Montfermeil whom he had so long and so vainly sought! He had found him at last, and how? His father’s savior was a ruffian! That man, to whose service Marius was burning to devote himself, was a monster! That liberator of Colonel Pontmercy was on the point of committing a crime whose scope Marius did not, as yet, clearly comprehend, but that resembled an assassination! And against whom, great God! What a fatality! What a bitter mockery of fate!
This is a moment in which a long-running instance of dramatic irony is finally fulfilled—readers have waited hundreds of pages for this to happen. For a long time, Marius has felt a certain duty and devotion to this unknown Thenardier who saved his father’s life. When he learns that Thenardier is nothing more than a common criminal, his world is shattered. This is also an instance of situational irony, since the man who was a hero for the ages only moments ago in Marius’s mind has now been revealed to be a lowly criminal. The irony that his father's hero turned out to be a dirty thief is painful for Marius, who is so strongly ruled by ideals and dignity. Marius is very shaken now that the hard truth has been revealed.
When Cosette and Jean Valjean settle at the Rue Plumet, Jean Valjean finally feels at peace. The narrator underscores his joy and gratefulness with situational irony:
When Cosette went out with him, she leaned on his arm, proud and happy, in the plenitude of her heart. Jean Valjean felt his heart melt within him with delight, at all these sparks of a tenderness so exclusive, so wholly satisfied with himself alone. The poor man trembled, inundated with angelic joy; he declared to himself ecstatically that this would last all their lives; he told himself that he really had not suffered sufficiently to merit so radiant a bliss, and he thanked God, in the depths of his soul, for having permitted him to be loved thus, he, a wretch, by that innocent being.
Jean Valjean is struck with joy by the sight and presence of Cosette in his life, especially after having endured so much hardship. It is ironic that Jean Valjean believes he has not “suffered sufficiently” to warrant such happiness, when he has in fact faced adversity for more than 25 years. He has endured several lifetimes of loneliness, pain, and slander. As much as any good-hearted character in the novel, Jean Valjean deserves to be loved for all he has done to redeem himself in the eyes of God and the people.
The story also metaphorically illustrates the warmth and utter contentment he feels to be a father to Cosette: “[He] felt his heart melt within him.” In this moment, when Jean Valjean's heart melts, he is settled, feeling as though he could stay with Cosette, her leaning on his arm, forever. He also demonstrates vulnerability for the first time, as he finally has someone to love and perhaps fearfully lose.
When Jean Valjean saves the severely injured Marius, he drags the young man's body through the sewers of Paris to find safety from the barricades. Jean Valjean prays to God after narrowly avoiding death in a nook full of quicksand, which the narrator frames with situational irony:
As he emerged from the water, he came in contact with a stone and fell upon his knees. He reflected that this was but just, and he remained there for some time, with his soul absorbed in words addressed to God. He rose to his feet, shivering, chilled, foul-smelling, bowed beneath the dying man whom he was dragging after him, all dripping with slime, and his soul filled with a strange light.
Finding solid ground in the treacherous, life-stealing muck, Jean Valjean feels a “strange light” in his soul. This heavenly moment is juxtaposed against the revolting situation of being stuck in the “foul-smelling” sewers with Marius’s near-dead body. Jean Valjean's feeling of lightness in the sewers beneath the Seine is ironic. He is both “absorbed in words addressed to God” and “dripping with slime,” touching the heavens while slogging through the bottom of Paris. Jean Valjean is never afraid to get his hands dirty and risk his skin to help others, no matter the consequences. Even stuck in the sewers, Jean Valjean's mercy and kindness to Marius lights up his soul in the eyes of God.
Javert is completely derailed when Jean Valjean, the notorious fugitive, saves his life and lets him go free. The narrator points out the irony of the situation:
To owe his life to a malefactor, to accept that debt and to repay it; to be, in spite of himself, on a level with a fugitive from justice, and to repay his service with another service; to allow it to be said to him, “Go,” and to say to the latter in his turn, “Be free”; to sacrifice to personal motives duty, that general obligation, and to be conscious, in those personal motives, of something that was also general, and, perchance, superior, to betray society in order to remain true to his conscience; that all these absurdities should be realized and should accumulate upon him, this was what overwhelmed him.
It is situationally ironic that Javert owes his life to his "malefactor" Jean Valjean, whom he has hunted with malice for so many years. Javert becomes so overwhelmed by this wretched convict’s act of kindness that his entire ideal system comes crashing down. The irony proves tragically powerful when Javert subsequently throws himself into the Seine.
By saving Javert’s life at the barricades, Jean Valjean unintentionally sentences Javert to death anyway. Unable to comprehend Jean Valjean’s mercy in light of the convict's rugged history, Javert loses his sense of right and wrong and, consequently, his place in the world. In the end, he decides to leave the world behind for good.