What are the main connections between Spencer, Aria, Emily, and Hanna? What secrets and situations bind them together even though they’ve all grown apart?

How did Alison treat Spencer, Aria, Emily, and Hanna when they were all friends in seventh grade? In turn, what were their feelings towards Alison at the time?

In what ways have Spencer, Aria, Emily, and Hanna changed since seventh grade? Who do you think has changed the most? Provide examples from the novel to explain your answer.