How does Twain use parallel scenes in the first 15 chapters of Huckleberry Finn?

Basically, Twain uses parallel scenes in the first 15 chapters of Huckleberry Finn to lay the foundation for Jim and Huck's developing friendship. This friendship is an important one, as it is of central relevance to the plot.
In Chapter 7, Huck makes his escape from his father's cabin. He fakes his murder by spreading pig blood all over the floor. For good measure, he smashes the door with an ax to give the impression that he was ambushed by thieves. Then, Huck hides in the canoe. When night falls, he makes his way down the river, barely missing his father (who has just returned). Huck ends up on Jackson Island.
While all this is happening, Jim is making his own escape. In Chapter 8, we learn why Jim ran away: he had overheard Miss Watson discussing the terms for his sale. Deciding that he would rather run away than be sold to a slave trader for eight hundred dollars, Jim ends up on Jackson Island, where Huck is staying. In Chapter 9, Jim warns Huck that the rains are on their way, so the two camp out in a vast cavern on higher ground.
A few nights later, the two friends discover a frame house floating down the river. There is a dead man's body in the house, but Jim covers it up with old rags. The man appears to have been shot in the back. The reality is that the dead man is Huck's father, and Jim wanted to spare Huck the pain of knowing this. This chapter is an important one, as it highlights the affection Jim feels for Huck.
In Chapter 10, Huck reveals that he is beginning to care about Jim's welfare as well. So, when Huck's prank goes wrong and Jim is bitten by a rattlesnake's mate, Huck tries to hide the evidence of his guilt. He doesn't want to hurt Jim, who he is beginning to care about. While all this is going on, a group of people are looking for Huck's supposed murderer. Unfortunately for Jim, everyone thinks that he's the killer. This new development poses a great threat to the two new friends, so they must stay together and remain focused on their main objective.
By Chapters 14 and 15, the two have plotted to head north together, to the free states. So, Twain effectively uses parallel scenes (with concurrent events involving different characters) to lay the foundation for a friendship that is central to the novel's plot. It is Huck and Jim's partnership that drives much of the action in the rest of the novel. So, the use of parallel scenes is an important literary device.