How does the author use foreshadowing in The House of the Scorpion?

In Chapter 22, Matt does not want to risk Maria's life by attempting to escape through the tunnel by pressing the red scorpion, but she refuses to leave him again, saying she loves him though it is a sin and she will probably go to hell for it; Matt promises to go with her if he has a soul. This fulfills earlier foreshadowing and foreshadows that Matt and Maria will eventually be together.