When Jason first walked into the Halloween party, dressed as a very sexy James Dean, he spoke with his half-sister Spencer (Troian Bellisario) briefly, explaining that he’d just needed some time away from all of the drama in Rosewood.
But then, out of the corner of his eye, he spots Lucas, who was still taking pictures with his vintage camera. They give each other a knowing look, and then Jason follows him behind a door. Later, Jenna (Tammin Sursok) sees Lucas’s camera laying on a table and smiles to herself, almost as if she knows that Jason and Lucas are together.
We can think of a couple of reasons why those two would be conspiring together. For one thing, we think Lucas knows a lot about the night Alison’s (Sasha Pieterse) body was stolen. He was seen walking around Rosewood that night, and Aria found those pills in his bag, suggesting that he was one of the people who drugged Emily (Shay Mitchell).
What if Lucas wanted to tell Jason the truth about his sister’s body? Maybe he’s starting to feel badly about being on Jenna’s team of body thieves, and wants to set Jason’s mind at ease. It’s also possible that Lucas and Jason are both on the “A” team and just needed a secret place to meet. After all, why else would Jason be at a high school Halloween party?
Another possibility is that Jason wanted to talk to Lucas about those questionable pills, and possibly a drug problem. Lucas did seem very twitchy, and we already know he carries prescription pills in his backpack. Plus, we know that Jason now works as an anti-drug counselor to high school students due to his druggy past. Maybe Jason realized that the Halloween party would be the only way he could approach Lucas without catching him off-guard.