In a way, the only real topic of this novel is injustice and mistreatment. It's in every power relationship, every financial interaction, every family dynamic, and every meeting between the governing and the governed. The narrator's tone matches this subject; his voice always sounds like he's about two steps away from launching into a screaming fit. He's also always hovering on the line between rage and passive-aggressive snarkiness. It's an interesting choice, since it makes the narrator sound very concerned about the characters and plot, rather than removed and judging them from on high – a tone Dickens uses to pretty awesome effect in other novels. Here, instead, we've got this voice:
'I have had the pleasure of seeing it under many circumstances during the last three years, and it's--a Paradise.'
It was (at least it might have been, always excepting for that wise resolution) like [Henry Gowan's] dexterous impudence to call [the Meagleses' house] a Paradise. He only called it a Paradise because he first saw [Pet] coming, and so made her out within her hearing to be an angel, Confusion to him! And ah! How beaming she looked, and how glad! How she caressed the dog, and how the dog knew her! How expressive that heightened colour in her face, that fluttered manner, her downcast eyes, her irresolute happiness! When had Clennam seen her look like this? Not that there was any reason why he might, could, would, or should have ever seen her look like this, or that he had ever hoped for himself to see her look like this; but still--when had he ever known her do it!
He stood at a little distance from them. This Gowan when he had talked about a Paradise, had gone up to her and taken her hand. The dog had put his great paws on her arm and laid his head against her dear bosom. She had laughed and welcomed them, and made far too much of the dog, far, far, too much--that is to say, supposing there had been any third person looking on who loved her.
She disengaged herself now, and came to Clennam, and put her hand in his and wished him good morning, and gracefully made as if she would take his arm and be escorted into the house. To this Gowan had no objection. No, he knew he was too safe.
There was a passing cloud on Mr. Meagles's good-humoured face when they all three (four, counting the dog, and he was the most objectionable but one of the party) came in to breakfast. Neither it, nor the touch of uneasiness on Mrs. Meagles as she directed her eyes towards it, was unobserved by Clennam. (1.17.11-18)
We're firmly on Arthur's side here, totally irritated by the obnoxious Gowan and his easy, throwaway charm. But because the narrator isn't Arthur, we not only get to root for Arthur, we also get a little outside perspective on his actions and reactions. Gowan here is obviously the cool guy rubbing his success with the ladies in nerdy Arthur's face. The narrator catches Arthur's anger at Gowan's mad complimenting skillz – by calling the house a Paradise in Pet's hearing, he is implying that Pet is an angel. Smooth move. And immediately we get Arthur's sad realization that Pet has the hots for Mr. Popular; he sees her look at Gowan like she never would at him – you know, with desire.
But just at this point, so we don't get sucked too far into Arthur's world, the narrator pulls back to remind us that Arthur is actually trying to pretend like he doesn't have feelings for Pet – a pretty lame lie that points to the weaknesses in Arthur's own character rather than simply dwelling on everything that's wrong with Gowan. Then, just like that, the narrator laughs a little to see Arthur is forever trapped in the friend zone, taking Pet into the house without any jealousy on Gowan's part. In a final switch, the narrator pulls out even farther and shows us how worried the Meagleses are about the whole Gowan infatuation.