The 13½ Lives of Captain Bluebear/WMG
Bluebear is an Unreliable Narrator.
He's already an in-story expert liar and storyteller, and even if he's passing off this story as truth, he may at least be changing a few details here and there for it to make a better story. This would explain any differences in details and characterizations between this story and Rumo and His Miraculous Adventures, particularly in Rumo and Smyke, whose appearances here seem a little jarring compared to how they're portrayed in Rumo.
If Bluebear is an Unreliable Narrator, the two stories could fit together relatively painlessly -- after all, after Bluebear and Mac save Rumo as a puppy in Captain Bluebear, Bluebear is away at school for several years, then an unmeasured time passes when he's in the dimension hole, he's with the Muggs for a long period of time, spends around two years inside the tornado and then a few weeks in the Bollogg's head before he meets Rumo and Smyke in Atlantis. The events of Rumo could easily have taken place within those years; there's even enough time for Smyke to eventually have moved to Atlantis and made it big there.
From here, there are a few possibilities:
- Events happened exactly as Bluebear describes them, but Bluebear misunderstood or lacked the proper information to get the real story. Hence, he gets a few things wrong -- for example, nobody told him that Rumo and Smyke were good friends, so he thought Rumo was just Smyke's bodyguard. When Rumo makes an off-hand remark about his family, he's probably referring to Ralla -- except that name wouldn't mean anything to Bluebear, so it's not mentioned. Smyke's villainy is a bigger point of concern here, since Smyke's role in Rumo was that he changed and became a better person, but it's possible he had a relapse when he moved to Atlantis -- or, possibly he was not as deeply involved in the crimes as everyone says he were, since we don't actually get his villainous deed confirmed by Smyke himself.
- Events happened more or less as Bluebear describes them, but he changed details around when telling the story, among other things made Smyke more villainous in order to either simplify or make the story more exciting.
- Bluebear never actually met Rumo or Smyke, he just added two well-known figures of Zamonian legend (Rumo does say how Rumo becomes a famous hero, so Bluebear might have heard of him) to his story to garner some interest.