~PLL Aria PArt of "A" teAm - Based on Camp Mona & events shortly after: THEORY/CLUES
At Camp Mona, when Hanna was trying to figure out who "A" was, she saw Aria and Ezra. Noel saw them as well. Aria must have known, before Hanna revealed this to the girls, that Hanna saw Aria and Ezra, because this would have been easy to figure out thanks to Hanna's calls to Aria right when Noel was writing "I See You" on Ezra's car. It should have been obvious to Aria that Hanna saw what
happened between her and Ezra, and at this point Aria was still keeping everything with Ezra a huge secret.
EDIT: Keeping this secret was incredibly important to Ezra, also. We now know that he was using Aria for research, even if he did fall in love with her. That would explain why he was so freaked out about "A" knowing about his relationship with Aria. That could have ruined everything for him.
Aria saw Noel, too! She told this to Noel in "Moments After." We thought that Aria was freaked out because she thought that Noel hit Hanna with the car. We could have been very wrong about this. Aria could have been so weird/paranoid about Noel because she thought he saw EZRA hit Hanna with the car.
EZRA could have hit Hanna with the car. According to the "A" text the girls received right after Hanna was hit by the car, Hanna "knew too much." Hanna only learned two things that night, what was going on between Aria and EZRA, and that Noel wrote the "I See You" message on Ezra's car. Aria and Ezra definitely had the most at stake in terms of things that Hanna knew, and it would make the most sense if the "she knew too much" text came from her OR EZRA. Aria had been in Ezra's car right before Hanna texted the girls that she knew who "A" was. Ezra could have easily seen this text. He knew that if Hanna exposed the identity of "A," this could be incredibly dangerous to Alison, more dangerous than the girls even realized at the time.
Aria was the one who received the "She Knew Too Much" text. Perhaps the horrified look on her face that followed was because she deduced that Ezra had hit Hanna with the car, or that he was involved in Hanna's "accident." Also, Ezra could have been so freaked out about the "I See You" message for multiple reasons. Yes, he was correct that someone did see him with Aria, but we didn't realize at the time how dangerous that actually was. We thought it was about a relationship getting ruined, and it could have been something much deeper than that.
If Ezra thought Hanna knew who ALISON'S "A," was, Hanna revealing this information could have potentially got the girls killed. If Ezra was telling the truth about when he learned Ali was alive, then at this point he "didn't" know. I'm not sure if I believe this, but the outcome would be the same either way. Ezra at the very least knew that "A" tried to kill Ali, and maybe he still believed that "A" DID kill Ali. If he knew Ali was still alive, he would have known that "A" being outed could get Ali killed for real this time. Even if he thought Ali was dead, he had fallen in love with Aria, so he would know that if Hanna spilled this information, "A" could have very well tried to kill Aria and the rest of the girls. Also, if Hanna exposed the Ezria relationship, he knew that it might screw up his research. He had to stop Hanna immediately and rashly. Maybe HE hit Hanna with the car or enlisted Mona to do it.
Mona, as "A" spying for Ali (I still think they might secretly be working together whether they like it or not), could have seen EZRA hit Hanna with the car and guessed, based on this, that Aria was Ali's "A." This could be why she called Aria "Big A" in a later episode. Mona could have been purposely rude to Aria in front of Ezra, during the play, to lead Ezra to believe that Aria was Ali's "A." Mona probably knew about Ezra's book already and that he knew about Ali's "A." She could have already been trying to help him figure out who it was at this point. Mona has never denied hitting Hanna with the car, but Mona is not the most trustworthy character in this show. If she saw EZRA hit Hanna with the car and knew about Ezra's suspicion that one of the girls "killed" Ali, she could have assumed that Aria almost killed Ali, it'd make sense for Mona to be terrified of Aria. Maybe Ezra hit Hanna with the car, but Mona is too afraid to tell anybody what happened, and at this point figures that nobody would believe her. Or, as mentioned above, maybe Ezra made Mona hit Hanna with the car.
We now know that Noel has been helping Alison and that he knew she was alive. According to Ali, Noel "has secrets, too." Maybe he did see EZRA hit Hanna, and already knowing about Ali's "A," suspected that Aria was Ali's "A," and/or that Aria was being forced to be Ali's "A" by Ezra. It's possible that based on secrets that Alison had already trusted him with, Noel already suspected Ezra of something or thought that Ezra could lead him to more information that could help Ali. That could be the real reason that he followed Aria to Ezra's car on the night of Mona's party. Noel has also been seen in season 1 lurking around the high school after hours spying on Ezra. This was never properly explained, even if Noel did claim to Aria that he noticed that Aria acted strange around Ezra. Noel could have thought Ezra and/or Aria was Ali's "A," and revealed his suspicions to Alison.
We learned from Grunwald that it's possible Ali didn't trust one of the liars, and that one of the liars was touched by the one Ali fears the most. People assumed that Grunwald was referring to Spencer, but she could have meant that Aria was the liar that Ali didn't trust, and that Aria had been touched by Ezra. We don't know how long Alison has trusted Ezra, or even that she was really telling the girls the truth about him. Ali could have suspected Aria AND Ezra because of Noel's allegations. This could also explain why Noel initially offered to help Aria get Ezra into trouble after he saw Aria and Ezra during Camp Mona. He could have assumed that Ezra was the person who hurt Ali and that he was threatening to hurt Aria too.
On Hanna's cast, "A" apologized to Hanna for losing her temper. After Hanna got hurt, Aria was incredibly nice to Hanna, nicer than usual. If Aria knew that her relationship with Ezra caused Hanna to get hit by a car, it would make sense for her to feel incredibly guilty. This could explain why when Hanna almost got Ezra and Aria caught by Ella because of "A," Aria was furious at first, but quickly figured out how Hanna felt about being forced to do what "A" wanted. People have suggested that Aria may have some sort of personality disorder and/or memory issues similar to the ones Spencer has. It's possible that when she initially was angry with Hanna, she was blaming some mysterious person, then she remembered that she (Aria as "A") made Hanna try to clue Ella in on the Ezria relationship.
When Aria forgave Hanna for almost outing the relationship, she mentioned that Hanna stopped Ella from catching them, and that made a big difference. Hanna never told Aria or the other girls about Caleb preventing Ella from getting to Philadelphia in time to catch Aria and Ezra on their date. Did Aria already know because she is somehow involved with "A"/ the A Team?