Oliver, relieved to hear that Rose will recover from her fever, takes a walk outside to clear his head. On his return to the Maylies' house, he runs into Giles, in a post-chaise (a kind of carriage), with an unnamed gentleman. Giles is still in his nightcap, as they have come to the Maylies' home very quickly. The gentleman asks Oliver whether Rose has gotten better—Oliver says she has, and the man, also quite relieved, introduces himself as Harry Maylie, Mrs. Maylie's son, and Rose's cousin.
Harry comes flying at full speed into the narrative. A dashing young man, whose "brilliant future" is sketched only in the broadest of terms by Dickens, Harry is more or less the archetype of the romantic hero: he is handsome, intelligent, and so devoted to his female love interest that he is willing to forgo all his life's advantages in order to win her.
Harry runs inside and finds his mother, whom he upbraids, gently, for not telling him sooner of Rose's illness. Mrs. Maylie counters that it would not have mattered—if Rose got worse, she would have died before Harry had had a chance to arrive. Mrs. Maylie and Harry have a conversation, in general and abstract terms, which seems to indicate that Harry has a genuine romantic love for Rose, and that some secret of Rose's, which causes her to have a "tainted" family history, keeps Harry and Rose from being happily married.
Rose's "tainted" family history is not elaborated in this scene, but it is described later in the novel, when Dickens (via the narrator) explains that, because Rose is the far younger daughter of Agnes, who gave birth while unwed, Rose has been "afflicted" with the scourge of Agnes' sin. Victorian audiences would not have found that sort of "scourge" to be altogether surprising, although modern readers often have difficulty understanding the gravity of Agnes' "crime" or how it could be seen as affecting her sister.
Harry and his mother leave off the subject for the time being; Mrs. Maylie goes back to tend to Rose, and Harry entertains Oliver, Losborne, and Giles with stories into the night. Over the next several days, Harry stays at the home, and collects flowers with Oliver to arrange for Rose.
Again, Harry is a figure everyone in the family adores, not just Rose; Giles and Losborne, in particular, seem taken with him. Harry's relationship with Oliver is not developed very much in the novel, but one infers that Oliver looks up to Harry a great deal.
One late afternoon, as the sun is setting and Oliver is seated in his room, reading and studying, he wakes up, slowly, to spot Fagin and the man he saw on the street (the "strange man," after Oliver had dropped off a letter for Losborne in the nearby market-town) outside the window. In a daze, Oliver cannot do anything, and he watches them disappear; once he wakes up fully, however, he runs out of the room and calls the rest of the family, asking for their help.
Another "appearance" of Monks. Again, at first this seems improbable, but then one learns, later on, that Monks and Fagin have been in cahoots; it would have been easy for Monks to tell Fagin that Oliver is living at the very house he robbed; and therefore the two could easily have found an opportunity to visit Oliver there.