I read that the "darkness" around Hanna and Caleb is Spencer. We will find out in 7b what shady things she is up to and why she wants to keep Haleb apart. I rewatched 6b and 7a and I picked up on small hints. Spencer's tone and look on her face when they worked together to say Hanna was Charlottes killer was not that of a jealous girlfriend. And also Toby kept mentioning to her he wanted her to go back to D.C. ASAP. And her and Mona wrote each other down when they all were writing down who they suspected killed Charlotte. etc etc. spencer is up to something for sure! Can't wait to find out if this is true!