Tattoo
At night, Aiden and Ethan are out on the streets of Beacon Hills, attempting to recapture teenage beta Isaac Lahey, who had escaped from the alphas' lair back at the bank with the help of the mercenary called Braeden. They pinpoint their targets' location and move on a high-speed chase through the streets.

The chase continues throughout the district until the twins chase Braeden's bike through a window. Isaac, exhausted droops on the woman's shoulder and they fall to the ground. Aiden and his brother then move in on their targets, walking in tandem, zeroing in on the weaker werewolf. The twins continue to advance on Isaac determined to snatch and bring their hostage back. Claws out, they rip off their tops, taunting Isaac. The weaker werewolf can only just crawl but resolutely stares back at his tormentors.

However, Braeden comes to, and shouts at Isaac to duck, while Ethan and Aiden rush forward with their attack. Braeden fires her modified military grade taser, and an electric bolf hits the merged twins square in the chest. The merged wolf falls back from the shock, spliting back into two separate individuals. In the electrical flash, Aiden and Ethan however, recover before Braeden and Isaac can regain their senses.

The twins eventually spot Braeden talking to Lydia Martin and Allison Argent. They disperse and rally their superiors to the high school.
The twins with the rest of the alphas chase Braeden down at the school, They corral her into the locker room. All five alphas attack the mercenary who puts up a good fight nonetheless, but she is eventually incapacitated. They then hand Braden off to Deucalion.
Chaos Rising

The twins are then seen in the library. His brother makes friendly with Danny. Aiden is seen in conversation with Lydia Martin. He later revealed that the only reason he talked to Lydia was because he knew that she may be important to Scott.
Unleashed

Once they have an opportunity, they rush off the track and mask their scent. Once the beta rounds the corner and looks around they ambush him, sending him tumbling across the terrain.
The alpha brothers then capture Isaac in an unrelenting hold. Isaac stares back up at the bullies with contempt.
Aiden: "Ethan, I always forget. How many bones in the human body?
Ethan: "I don't know. Let's count.

Both parties regroup with the class, with everybody looking in horror at a young male murdered and strung up against a tree. Aiden shares a look with his brother knowing it's a druidic sacrifice.
Later in the day, the twins draw Isaac out with scent again during class time. The alphas side by side face down the beta in the hallway. A fuming Isaac charges towards the brothers, eager to get back at them.

Aiden is next seen flirting with Lydia, asking to meet with her tonight, within Scott's hearing range, now plotting to get on the other beta's nerves. Later on when Isaac is assigned to restock the supply closet with Allison Argent. The twins have now shoved a vending machine against the closet door, knowingly triggering Isaac's claustrophobia so he'd have a meltdown, and this nearly has him savaging Allison if not for Scott's interference.
Aiden and his brother are both in the last class of the day, Jennifer Blake's English class.

Aiden: "Get off my bike!!"
Isaac: "No problem.
Isaac casually flips over Aiden, landing several feet away leaving Aiden standing next to his bike, just as the school sees him with his bike in the middle of the hallway. Jennifer is angry yelling at a surprised Aiden he's suspended for his apparent shenanigan. The twins glance in Allison, Scott and Isaac's direction and are pissed.
Isaac and Scott are pleased to have gotten revenge on the twins just as Aiden and his brother walk up to them with expressions that scream murder.

The melded twins give chase, outmatching the two werewolves, roaring gleefully. All of a sudden, Deucalion appears, and the merged twin is immediately submissive. He dissolves back into individuals Ethan and Aiden. Their leader swiftly slashes them both across their faces with the dagger in his cane. The fuming twins then follow Deucalion out of the building, but not before giving looks at the betas promising payback.
Frayed

Lydia: "Your hands." (Aiden removes his hands from her waist) "What am I? A nun? Put them somewhere useful."
Aiden: (hoists her up and cups her backside) "Is that better?"
Lydia: "Moderately."
Aiden is shown in flashbacks during the fight between the Alpha Pack and Derek's pack. He is also shown in a flashback making out with Lydia. He later helps Kali get treatment for Ennis by Deaton. He comforts her after Ennis dies.
Currents
Aiden is first seen in the episode making out with Lydia. Later, both he and Ethan hold Jennifer captivae during the attack on Derek's loft. They help with the killing of Boyd while there.
The Girl Who Knew Too Much
Aiden tells Ethan to stop talking to Danny. He is later seen making out with Lydia until she confronts him about killing Boyd. Aiden fights with Cora in the changing room until Ethan and Scott stop him. Aiden is seen at the concert with Ethan.
The Overlooked
Aiden and Ethan search the hospital looking for Jennifer Blake. They have multiple physical encounters with Scott, Derek, Peter, Allison and Chris.
Alpha Pact
Aiden and Ethan help Deucalion and Kali hunt down Ms Morrell.
Lunar Ellipse
Aiden and Kali go to kill Derek iin his loft. Ethan and Lydia go to convince them not to. While there, Jennifer shows up. The twins merge together and attack Jennifer. She breaks their neck. Deaton manages to save Aiden and Ethan. They are no longer Alphas and they can no longer merge together.
More Bad Than Good
Although Aiden and Ethan are not Alphas anymore, Scott seeks them out to help him control his werewolf side now that he is an Alpha. They teach him control and not be afraid to turn.
Galvanize
Aiden and Ethan try to join Scott's pack. But Scott says that he doesn't trust them and turns them down. When police say that William Barrow has been sighted near the school, the twins help Scott's pack search for him.
Illuminated
Trying to prove to Lydia that he is not a "bad-guy", Aiden helps Danny set up a Halloween party. While there, he is marked by the Oni.
Silverfinger
Aiden and Ethan offer protection to Scott to try and gain his trust so that they may join his pack. They help protect him when the Oni try to mark Scott and Kira at Scott's house.
Riddled
Aiden helps Lydia search for Stiles. He tells Derek of his suspicions that Stiles helped Barrow.
Letharia Vulpina
Ethan and Aiden help Scott find Stiles
Echo House
Aiden and Ethan help Scott find a scroll that belonged to Silverfinger.
De-Void
Ethan says that he and Aiden might not stay in school. They become controlled by the Nogitsune and fight with Isaac, Allison and Kira.
Insatiable
Aiden and Ethan try to find Lydia. While looking for her, they are shot with wolfbane bullets. They are saved by Derek despite being shot by several bullets.
The Divine Move
Ethan and Aiden want to run, but Derek convinces them to stay and fight. Aiden kills an Oni with one of Allison's silver arrowheads. As he does, he gets stabbed in the stomach. It's a fatal wound. Ethan cradles his brother while he's dying. Aiden asks him if it hurts him, too. He then laments that Lydia will never know that he died as one of the good guys, but Derek vows to tell her because she'll believe him.