Panel 3 here calls back to Captain Hookeye and Mr. Glee, the pair of ghosts Gravedust raised and avenged in his (chronologically) first adventure with the soon-to-be-Peacemakers.

Panel 4 does not refer to any one moment we’ve seen, but it does encapsulate a lot of Frigg and Gravedust’s scenes together, especially in Chapters 13 and 27. Frigg giving Gravedust an aggressive eye-roll is just Frigg being Frigg: the fact that she’s listening to him at all is the accomplishment here. This relationship of theirs won’t be as visible in chapters to come: Frigg is starting to outgrow the need for father figures… but one of the reasons for that growth is that Gravedust has done his job as one.

Panel 5 shows Gravedust’s recent failures: a spirit he failed to avenge and a woman whose spirit he failed to save, leading to the destruction of both and doubts about his life’s purpose.