In a moment of tragic situational irony, Raymond laments that his mistress does not realize how good she has it while also explaining that he abuses her:
You see, Monsieur Meursault, it’s like I told her: "You don’t realize that everybody’s jealous of how good you have it with me. Someday you’ll know just how good it was." He’d beaten her till she bled.
This dark moment is one of situational irony, as the fact that Raymond physically abuses his girlfriend is misaligned with Raymond's adamant urging that his girlfriend is living a good life with him. Domestic violence is one of the many dark themes that The Stranger deals with, although Raymond's brutality does not appear to disturb Meursault, who consorts with Raymond regardless. This moment reaffirms Meursault’s apathy: someone who agrees to write a letter that will trick a woman into returning to their abusive partner, only for that partner to beat her up again, is not just apathetic but actively cruel.
There is another level of irony that the reader might recognize if they have read The Stranger before—namely, that in Book 1, Meursault himself does not realize how good he has it. While he is suffering from a headache in this scene, and while he does not articulate many pleasant emotions both generally and in this scene specifically, once he is sentenced to death, Meursault becomes entirely divorced from his life as he knew it. He laments the physical experiences he can no longer have in prison, like swimming on the beach or being with Marie, although he also deeply appreciates the memories in and of themselves and, interestingly enough, eventually comes to accept both his nostalgia and the fact that he will never experience such things again.
Despite initially appearing to despise his dog, dragging him along on walks and beating him frequently, Salamano ironically becomes distraught when the dog runs away:
He was looking down at the tips of his shoes and his scabby hands were trembling. Without looking up at me he asked, “They’re not going to take him away from me, are they, Monsieur Meursault? They’ll give him back to me. Otherwise, what’s going to happen to me?” I told him that the pound kept dogs for three days so that their owners could come and claim them and that after that they did with them as they saw fit. [...] from the peculiar little noise coming through the partition, I realized he was crying. For some reason I thought of Maman.
The situation is ironic in that the old man drove the dog away by beating it, only to then weep over its disappearance. The notion that people don't know what they have until it's gone comes up again and again throughout The Stranger, from Raymond and his mistress to Meursault and his introspection while on death row. It also shows the complications and contradictions that make up who people are: one page earlier, Salamano proclaims “pay money for that bastard—ha! He can damn well die!” before later being brought to tears over the dog. Salamano feels incredibly negatively, and incredibly positively, toward his dog, caught up in the contradictions of feeling. The inability to understand life is, for Camus, foundational to the absurd, and it is demonstrated in these unintelligible contradictions.
Salamano, in demonstrating a deep emotional attachment to his dog, also serves as a foil for Meursault, whose apathy is his defining characteristic. While Meursault "for some reason" thinks of Maman after hearing Salamano cry, he doesn't connect that crying to his own emotions. Meursault, in other words, does not demonstrate the same emotional range of other characters in the novella. If Meursault thinks of Maman because he feels similarly to Salamno, he isn't able to admit that to himself or to the reader.
When Meursault first sees the group of Arab men allegedly following Raymond, he uses a simile to describe how they stare:
We were just about to leave when all of a sudden Raymond motioned to me to look across the street. I saw a group of Arabs leaning against the front of the tobacconist’s shop. They were staring at us in silence, but in that way of theirs, as if we were nothing but stones or dead trees.
This simile is used to describe how Arab men look at French men like Meursault—as if, according to Meursault, French men are just “stones” or "dead trees." The phrase "[i]n that way of theirs" dismisses the Arab men and their actions as those of a different group (an other), thus centering the French-Arab colonial conflict in a story that is fundamentally about the murder of an Arab man by a French man. Ironically, it is Meursault who treats people like objects, whether he is claiming that nothing changed after his mother’s death or that he is killing another person almost involuntarily. While Meursault does not recognize the humanity of the Arab people, he uses figurative language to paint them as failing to recognize the humanity of the French.