|“|| Theo: "Are you going to tell me what happened last night?"|
Hayden: "It was exactly like the painting. Exactly what you said."
Theo: "Have you told anyone else?"
Hayden: "I didn't think you'd want me to."
Theo: "You're right. [...] Look, that thing out there is going to kill a lot of people... but it's not going to kill us. Not if we're together. [...] Anything else you want to tell me?"
Hayden: "Not really."
Theo: "Look... I don't want this to sound like a warning, and I definitely don't want it to sound like a threat... But you can't hide anything from me, Hayden. Remember that."
Hayden and Theo first met due to their mutual alliances with members of the McCall Pack, as Hayden and her boyfriend Liam Dunbar had been captured by the Dread Doctors, and Theo helped the pack rescue them by breaking them out of their cell. However, it was soon revealed that Theo was actually working with the Dread Doctors, and the rescue of Hayden from their captivity was all staged to make the McCall Pack trust Theo.
When it became clear that Hayden was rejecting her transformation into a Chimera, Theo, needing her for his plans, tried to get the Doctors to postpone killing her, believing that failures tainted their experiment pool, but they would only agree to hold off until the supermoon before injecting Hayden with an overdose of Modified Mercury. After a brainstorming session with Liam, the two realized that an Alpha bite could cure her of her condition, which coincidentally caused a rift between Liam and his Alpha Scott McCall, who refused to give Hayden the bite out of a fear that it would kill her, further benefiting Theo.
By the time Theo's motives were finally exposed, Hayden had already died of mercury poisoning and was brought to the Nemeton by the Hellhound Jordan Parrish. However, when Theo's plans ultimately failed, he reverted to his back-up plan by stealing the Dread Doctors' Green Serum and using it to resurrect four of the dead Chimeras at the Nemeton-- Hayden, Tracy Stewart, Josh Diaz, and Corey Bryant-- and starting his very own Chimera Pack to rival that of the McCall Pack.
Hayden, suffering after-effects of her resurrection and not knowing what had occurred during and as a result of her death, was loyal to Theo at first, feeling a great deal of gratitude towards him for bringing her back to life, but her residual romantic feelings for Liam kept luring her back to the McCall Pack's way of thinking. It wasn't until Hayden had a conversation with Deucalion (who had allowed himself to be captured as part of Scott's plan to defeat Theo) that she realized that Theo's true loyalty was to himself, and that the "Betas" in his pack were only as valuable to him as they were useful in his quest for power. From then on, Hayden pledged her loyalty to the McCall Pack and ultimately became a member in her own right after receiving the bite from Scott while Theo was imprisoned underground by Kira Yukimura and the Skinwalkers.
When Liam proposed bringing Theo back to use his power stolen from Josh Diaz-- electromagnetokinesis-- in the pack's fight against the Ghost Riders, Hayden was understandably wary and hesitant, and even tried to stop Liam right before he freed him out of fear that their plan could backfire. In an interesting role reversal, Hayden, upon learning that Theo no longer had Josh's powers, saw him as useless to their cause and proposed they send him back, and was against destroying Kira's katana in case they needed to re-imprison him. However, Theo's knowledge of the Wild Hunt was invaluable to their fight to take back Beacon Hills from the Ghost Riders, forcing Hayden and Theo to become reluctant allies. Their reunion did not last long, however, as Hayden moved away shortly after the Ghost Riders' defeat, leaving Theo to take Hayden's role in looking out for Liam in her absence.
Throughout Teen Wolf Edit
In The Last Chimera,
In Lie Ability,
- Both Hayden and Theo were part-Werewolf Chimeras who looked similar as a result of their wolf-dominant hybrid nature-- both had the same glowing gold eyes, fangs, and claws typical of a Beta Werewolf.
- It was implied that Theo's eagerness to have Scott give Hayden the bite when she was dying of mercury poisoning was to see if a Chimera could survive the process, as also getting the bite from Scott would make Theo a Beta of Scott's own making, and thus someone who could successfully steal his Alpha powers.