In Season 5, Hayden is a new sophomore at Beacon Hills High School. She is a childhood nemesis of Liam Dunbar. She and Liam begin to make amends for their negative history, the two starting to fall for each other. Hayden is later revealed to be a werewolf/werejaguar Chimera created by the Dread Doctors. She is informed of the supernatural and her condition by Liam and brings her to Scott's Pack to protect her. During the struggle againt the Doctors, she and Liam start a romantic relationship. Hayden is however killed by the Doctors, but Theo revives her to be part of his Chimera Pack. Hayden wholeheartedly follows Theo, along with Corey Bryant, Josh Diaz and Tracy Stewart, as a result of her soul being broken and out of self-preservation. She and Liam reconcile and carry on their romance, and Hayden gradually regains her humanity and recommits to her original personality. To be with Liam, Hayden leaves Theo, fully recovering her sense of self, likewise with Corey. She is mortally wounded by Sebastian Valet, then Scott Bites her with her consent, transforming her into a true Beta werewolf ensuring her survival and she joins Scott's Pack.
Hayden is down-to-earth, modest and a very tenacious teenage girl. She can be short-tempered and snarky, not afraid of telling people what she thinks of them, and mischievous as she looks forward to getting back at Liam for his ruining her face back in sixth grade.
"So, ... you're not still pissed off about the sixth grade?"
Hayden (chuckles): "I'm not pissed off, Liam" - (seething) "I'm vengeful."
Nonetheless, Hayden is a rather caring, loyal and diligent person. She's has a close relationship with her sister taking a part time job to help her sister pay off the financial debt to her medication. Later on, she demonstrates a more empathic, warmer and braver side during the threat of the The Dread Doctors, coming to put her grudge against Liam aside and even fall for him.
After being revived by Theo, Hayden is broken and traumatized after having dying, a piece of her soul gone. She become more alert, paranoid, takes a higher sense of self-preservation and lacks self-esteem. She joins Theo's Pack without hesitation, overlooking the latter's treachery and duplicity.
Despite her darker persona, Hayden wants to ensure she survives for her sister's sake, knowing Valerie wouldn't be able to handle the feeling of her being dead and states that she only feels right whilst being with Liam. Soon afterward, inspired by Scott and Liam's persistent determination in helping people, Hayden overcomes her fear of dying again and starts to come back into her true personality realizing she'd rather do good with the McCall Pack than cause chaos with Theo. She displays a new sense of bravery, being empathic and supportive towards those she feels close to, including Liam, Corey and Mason, naturally coming into her own as part of Scott's Pack.
In sixth grade, Hayden and Liam were classmates. On the day of the yearbook pictures were taken, Hayden got caught in the middle of a fight that Liam was having with another kid. He'd accidentally hit her face as collateral damage, and her yearbook photo had her with a black eye and a bandaged nose. In vengeance, she broke Liam's nose and punched out his eyes.
Later on, Hayden got a kidney tansplant. To help her sister pay off the financial debt for her medication, Hayden gets a job at Sinema.