How does the author use foreshadowing in Special Topics in Calamity Physics?

In Stockton, Blue meets and befriends a woman named Hannah Schneider, who teaches film at the school. Hannah is friends and socializes with a group of elitist students, known as the Bluebloods. Hannah brings Blue into this group, which accepts Blue over time. Blue and the members of the Bluebloods are all curious about Hannah, who never reveals much of her own past. This foresshadows problems when they do find out about her past.