Marlene said she knew who was going to be A and AD since the beginning and that AD has been around since the beginning. That doesn’t need to mean that AD is on the pilot but he is in the first season.
Caleb’s first episode is 1x14 and three episodes later, Spencer calls him Artful Dodger. AD.
He lives in the school and has a little lair where he has a lot of phones, money…
Later, in the episode where Hanna and Aria find his lair, he literally appears as -A: black hoodie. And instead of talking to them he runs after the girls as if he was actually -A. Why doing that?
Both of his parents’ last names’ start with D (Dawson and Doyle) so his real last name starts with D.
He lived with Lucas. He and Caleb are the only characters that have appeared reading comics (arcturus hint).
He helped Jenna investigate the girls.
Caleb’s locker combination was 2-1-4. BAD.
When Mona was in Radley, Hanna wanted to visit her but Caleb didn’t want her to go because she could see Cece there or she could find out something from Mona.
Hanna saw Lucas visiting someone in Radley. She went there without telling Caleb but when she got out he was there. Caleb took Lucas there and stayed out because he was watching if someone went there so he could warn Lucas. Caleb was surprised to see Hanna there but then he said he knew she was going there. Lucas got out and they enchanged weird looks like the one Lucas gave to Aria in 7x16 and that look was intentioned.
Caleb wanted Hanna far away from Mona and Radley all the time. The only requirement for her to be there was with Caleb’s presence.
The mask he wore in the This is a Dark Ride appeared in the dollhouse besides Charles.
After he left for Ravenswood, he came back to Rosewood (and the show) in the same episode Lucas was having a party for his girlfriend (who never showed up). Caleb shows up. Was he the ‘famous girlfriend’ and was having a ‘welcome home’ party?
After the dollhouse, Caleb was shady and overprotective with Hanna. He even put a gps in her car. Who also likes to put gps on the girls? AD? A?
The girls went to find Charles/Charlotte’s Radley file to a storehouse and who appeared suddenly? Caleb. He admits to have put a gps on her car. I bet it wasn’t the first time he did it. He took it off but he still wanted to know everything about where Hanna was. He wanted to know if she/they find out something.
In the same episode (6x04) we find out that -A (Charlotte) was watching them because they had a gps chip on their napes. Caleb gave her the gps chips.
They were investigating Holbrook and they find a warehouse. The number of that warehouse (which they believed it was Holbrook’s) was 1017. Episode 1x17 is the same one where Spencer calls Caleb ‘Artful Dodger’.
After time jump clues and S7 clues (Marlene said to re-watch S7 for clues)
Caleb came back to Rosewood after Charlotte’s death.
It was then when he started his game. He wasn’t AMOJI.
He installed the cameras and the security system of the Radley so he could know everything. AD texted some things that happened there.
Caleb had a room at the Radley (said by Ashley Marin in 7x17) but we never saw the room. He was always in Spencer’s barn or in Lucas’ apartment. Suspicious.
Lucas had to meet someone in Radley at the same time Hanna had to find Spencer’s bill she payed with Rollins card. Since she took a while, Caleb had to help her and Lucas didn’t meet with that person because he wasn’t in the room.
AD’s boardgame appeared inside Spencer’s barn. She was shot and couldn’t grab weight but Caleb could have done a copy of the keys and left the game inside.
Hanna asked him for help with the board and he got hurt. That was the fakest incident ever. I mean, that’s an alibi that almost every villain plays: getting hurt from the ‘villain’. Besides, it wasn’t that bad…
He has the same computer that AD.
He has been missing in a couple of episodes.
He hastily asks Hanna if she wants to marry him and like two days after, they get married. He says: If we get married we can’t testify against each other. I MEAN HE’S LITERALLY TRYING TO SAVE HIS ASS.
Disclaimer: I’ve found some of these clues in instagram and twitter (@uberadictos).