A Pretty Little Plot Twist If It Were Up To Me (What I would add to PLL based on Melissa's behavior in Episode 4x03)
Melissa Hastings returns to Rosewood in this episode of PLL, and she brings a lot of new questions back to town with her. Her behavior towards Spencer in this episode indicates that there might be a lot more to Melissa's character than we realize. Melissa even points this out to Spencer herself.
Seemingly out of nowhere, Melissa is finding that she and Spencer have a lot in common, and she thinks that if they know what's good for them, they should both leave town. It's easy to chalk this up to typical Melissa Hastings weirdness, but I have a better idea.