|“||When you love someone, it's worth fighting for, no matter what the odds are.||”|
— Aria to Mike
Mike and Aria start off quite close. When Byron and Ella start fighting, Mike approaches Aria, feeling vulnerable, but Aria tells him that it isn't there business. Later Aria makes dinner for the both of them and they watch TV together. After their parents separate, he deals with it badly and gets into a fight in the hallway and when Aria arrives and breaks up the fight, Mike just pushes her away.
Soon after, Mike starts hanging out with Noel after Aria has broken it off with Noel. Mike innocently reports that Noel is planning to out Mr. Fitz' relationship with a student, Mike assures them that it is true as Noel said he saw them and was going to the principal's office the next day.
After Ella and Byron reconcile, Ella stops him in an argument about Aria which is overheard by Mike. When Aria returns home, Mike scolds her for keeping a secret from her parents that is causing them to fight again; he blames her for their fight. Aria and Mike had agreed to make dinner for the parents as a way to a family date night, but due to the argument, Ella cancels, leaving the three to eat dinner alone.
Aria notices a change in Mike because she goes to pick up Mike from the basketball courts but only finds Mike's "old" friends. When Mike comes home, She also confronts him about his lies, but he brushes her off, as he is not dealing with his transitioning family situation very well. Aria's dad picks up on Mike's abnormal behavior at home, but Aria denies what she knows, having been threatened by Mike.
In "The Devil You Know," Jason catches Mike trying to sneak into his house and takes him to the Montgomery's without calling the police. When Aria begins lecturing Mike about breaking into people's house, he says he will return all the stuff he stole from Emily's garage if it makes her happy. Aria pauses, and then begins to figure it out that he was the one who pushed her in the Hastings' house. Aria finds Jenna's vase that Jenna had made in Mike's stuff and accuses him of stealing from Jenna, but she is thrown for a loop when he tells her it was stolen from Officer Reynolds place; he claims to have actually stolen from a cop because he was looking for a gun.
Mike then, is diagnosed as clinically depressed and one day, Aria goes into Mike's room to tell him to go downstairs. Mike gets annoyed and tries to shoo her away, but she refuses to leave, trying to reason with Mike. Then Ella comes in to tell Mike to turn off his computer and make dinner. She firmly shuts the computer, but Mike gets violent, tries to get the computer back, and leaves his mother with a bruise before angrily walking away, while Aria was watching.
After Ezra and Aria come clean about their relationship to her parents, Mike punches Ezra causing him to bleed and leave. Later, he apologizes to Aria for punching him. He tells her that he did it only because he was scared Byron might do it first. He also shows her an escape route so that she can go to the greenhouse to meet the other Liars. Afterwards, Mike tells Aria that he knows she is still seeing Ezra even though their parents forbid. He doesn't understand why she just doesn't let him go to which she tells him when you love someone, it is worth fighting for.
While Aria tells her mother she should go with her boyfriend on a trip, Ella eventally says no. Aria confronts her about and Ella tells her Mike was not happy about her leaving. Aria confronts him about it and Mike says the only reason she wants Ella to leave is so she could hook up with Ezra. This hurts Aria and she runs away. Mike feels sorry about this and apologizes.
Mike and Aria's relationship is tested when Mike's friend Connor tells his friends that he and Aria hooked up when really he kissed her and she pushed him away. Mike believes Connor's lie and confronts Aria about it. After Aria confronts Connor and he calls her a slut, Mike apologizes to her about believing Connor instead of her. Mike promises Aria he won't let people like Connor go near his sister. When Mike is thought to have trashed Connor's car, Aria at first thinks her brother did it but refuses to believe it afterward. Aria is happy to see that her brother no longer is thought to have trashed Connor's car. Mike is mentioned to be in the same karate school as Aria afterwards.
When Mike starts dating Mona Aria shows her disapproval of the relationship. When Mona breaks up with Mike, he blames it on Aria, but the two soon become close again when Mike apologises.
Mike [to Aria]: I'm gonna make it up to you, okay?
Mike [to Aria]: I'm your brother. I'm suppose to watch out for you, stand up for you.