Allison is the beautiful new girl in town, and Scott's love interest. On her seventeenth birthday, her aunt, Kate Argent, gave her a silver medallion with the family crest that depicts a large snarling wolf and arrows. Kate tells Allison to “look it up” and find out what it means, implying that initiation into the family business may not be too far off.

Compared to her father and her aunt, Allison seems more gentle and compassionate. She demonstrated a care for animals in Wolf Moon, getting very upset when she accidentally hit a dog with her car then picking it up to take it to Scott at the vet clinic for care despite the animal’s agitated and potentially dangerous disposition. During the family dinner in Magic Bullet, she appeared to be near tears as her father recounted the tale of a rabid dog that had to be put down by her grandfather.

Allison ended her relationship with Scott in Night School, due to trust issues. She managed to avoid him in Lunatic. In Co-Captain, Allison begins to soften toward Scott. Kate Argent reveals the family secret by showing her Derek Hale as a werewolf.

In Formality, she initially shook up about it but gets over it and practices her archery on a wanted poster of Derek. She begins to focus on the Winter Formal and goes to the dance with Jackson, due to persistence from Scott for Jackson to protect her from Peter Hale. Eventually Allison ends up dancing with Scott. He kisses her and she asks, why did he do that? Scott admits that he loves her and they embrace with another kiss. Allison takes Scott outside so they can be alone. Later, Scott (through her father attacking him) reveals he is the second beta.

In Code Breaker, her parents attempt to send her and Kate to their home in Washington, but Kate gets her in on the hunt for the Betas. She shoots Derek twice with arrows and is about to shoot Scott, who tries to explain how he tried to protect her. However, she says she doesn't believe him. Only when Kate tries to kill Scott, does Allison finally change her mind. Kate is stopped by Chris Argent, who confronts Kate with her involvement in the Hale family house fire. Then she witnesses Peter Hale rip out her aunt's throat. Allison played a part in killing Peter Hale. With her cross bow, she shoots the self-igniting Molotov cocktail in Peter's hand and he begins to be burned alive. After Peter is incapacitated, Allison approaches Scott gently. Despite Scott being in werewolf form, Allison kisses him, turning him back into a teenager. When asked why she did that, her answer is that she loves him. At the end, she is last seen kissing Scott on her roof, showing she doesn't care he's a werewolf.