In Ice Pick, Erica was in gym class with Scott McCall, Stiles Stilinski, and Allison Argent. It was rock-climbing day led by Coach Finstock, and Erica was paired up against Stiles in climbing up the rock wall. However, Erica, who was already anxious to begin with, only got about half way up before she froze in fear and started to hyperventilate. When Coach believed that Erica was "freaking out," Allison reminded him that Erica is epileptic, which exasperated him before he helped her lower herself down, much to her embarrassment.
After the class ended and everyone left to change back into their normal clothes, Erica, desperate to prove herself capable of climbing the wall, starts to make her way up without a safety harness. Halfway up, Erica got an aura and pleaded with her body to stop before she began to have a seizure, and in a miraculous case of empathy, Scott, who was changing out of his gym clothes, rushed out and caught her before she fell off the wall onto the gym floor. Erica is then taken to Beacon Hills Memorial Hospital's emergency room, where she was assessed by Melissa McCall, who reminded her that she needed to keep taking her anti-seizure medications.
A little while later, Derek Hale appeared and wheeled her gurney into the morgue so he could speak with her privately. He listed all of the side-effects of her anti-seizure medications and remarked on how terrible they sounded before making her an offer that would mean she would never experience them again. Desperate to be free of her epilepsy and the social issues they caused, Erica immediately consented to the Bite and successfully transformed into a Beta Werewolf. The next day, Erica returned to school with a drastically changed style and personality, now feeling confident about her appearance and the power she gained from lycanthropy. She walked out of the school cafeteria, with Scott and Stiles following her outside and watching her get into Derek's Camaro, with both Werewolves smiling dangerously at the two.
The next day, she was approached by Scott in the hall, where he demanded to know who Derek planned on turning next, since he knew Derek needed at least three Betas to make up a fully-powered pack and that at this point, he only had Isaac Lahey and Erica. Erica responded that they wouldn't need to turn a third Beta if Scott would join them, but when Scott made it clear that he had no intention of doing so, Erica changed the subject. She went on to tell him about the time that she had a seizure in the middle of class; she claimed to have never remembered her seizures before that point, but that since one of her classmates recorded it on their phone, including when she unintentionally urinated in her pants, she was unable to forget because everyone made fun of her for it.
After school, she followed Stiles to Boyd's house after Allison, Scott and Stiles learned that he was Derek's final choice for a third Beta. She first attempted to distract him by seductively flirting with him, failing to get him to compliment her new appearance before she took a car part that she had stolen from Stiles' Jeep and beat him over the head with it and tossing him into a nearby dumpster. She then joined Derek, Isaac, and Boyd at the ice rink where Boyd worked, with the entire pack facing off against Scott when he attempted to talk Boyd out of accepting the Bite. While Scott successfully defeated Erica and Isaac, Derek dominated him easily due to his Alpha powers, and Boyd revealed that he had already been bitten by Derek.
In Abomination, after losing to Scott in a two-vs-one situation, Derek began training Erica and Isaac while Vernon Boyd, who was still in the early days of his transformation, watched curiously. Derek repeatedly slammed both of them onto the ground after they continued to use the same strategy every time, and finally suggested that they try something that wasn't so predictable.
Erica, rising to the challenge, lunged for Derek, wrapping her legs around his waist and kissing him passionately. Derek indulged her for a long moment before throwing her off of him and harshly instructing her not to do that again. Erica, embarrassed, assumed it was because she was just a Beta, but Derek corrected her by saying that it was actually because he had someone else in mind for her, implying that he was trying to get her and Scott together to make it easier to persuade Scott to join them.
That night, during the Beacon Hills High School lacrosse game, Erica caught Stiles rooting around in the principal's office, looking for the Argent Family Bestiary he thought may be hidden there, and forced him to follow her to the school's indoor swimming pool, where Derek was waiting for them. Derek and Erica demanded to know what Stiles saw during the mysterious reptilian shapeshifter's attack at the mechanic's shop several days earlier, with Derek puncturing a basketball with his claws to intimidate Stiles into complying.
Stiles reluctantly shared everything that he knew, and when it seemed like Derek and Erica recognized what he was talking about, he assumed that they had already dealt with something like this as well, not realizing until a moment later that the creature was actually above the stands. When the two Werewolves attempted to fight back, Erica was immediately knocked unconscious by the shapeshifter, while Derek was scratched on the back of the neck with its claws, exposing him to its paralytic venom that made Derek immobile from the neck down as he fell into the swimming pool, with only Stiles to help keep him afloat.
Once Scott arrived to help scare the shapeshifter away, and Derek and Erica each recovered from their respective injuries, the four of them met up outside of the school, where Derek admitted that, upon seeing the creature scamper away when it saw its own reflection in the broken mirror, he realized what they were dealing with-- a reptilian shapeshifter known as a Kanima that was essentially a mutated variation of a Werewolf. Derek then denied Scott's suggestion that they bring in the Hunters to help them and insisted that when he found the Kanima, he was going to kill it, before he and Erica left to return to the Railway Depot.
In Venomous, Erica was sent by Derek to Beacon Hills High School to retrieve Jackson Whittemore, where the young man was working out with his best friend Danny Mahealani. She then brought him back to the Railway Depot, where Derek wasted no time interrogating Jackson about what happened during the last full moon while Isaac Lahey and Vernon Boyd stood ready for back-up. Jackson insisted that nothing happened, and though Derek assumed he was lying, Jackson assured him that he wasn't and that he could prove it because he filmed himself that night.
When Isaac began making fun of Jackson for this, Jackson angrily ranted that it was the full moon, and that he was preparing for the "gift" Derek promised him, but he ended up getting nothing. He once again reiterated that he could prove his story if they let him go get the video, but Derek had a better idea-- he put on rubber gloves and picked up a shard of mirror that still had some of the Kanima's venom on it, stating that a snake can't be poisoned by his own venom as he approached Jackson with it. When Jackson began to protest, Erica and Isaac held him still so Derek could put a drop of the venom in Jackson's mouth.
To everyone's surprise, Jackson was paralyzed by the venom, just like everyone else who had been exposed, forcing Derek to reluctantly admit that, while he still thought Jackson was a snake, he just wasn't the one they were looking for. However, before they released him, Isaac bullied him into recanting his story with the police so he would no longer be a suspect in his father's murder.
The next day at school, it was made clear that Derek intended to test their other potential Kanima suspect-- Lydia Martin, who had been bitten by Peter Hale during his short stint as an Alpha but neither died nor seemingly turned into a Werewolf. While Erica and Isaac were walking down the hallway, Jackson, with his sporadically-functional superhuman senses, managed to hear Erica confirm with Isaac that Derek planned for the test to occur during history class. Isaac went on to say that if Lydia ultimately failed the test, he was going to "kill that bitch," though Erica reminded him that they had to test her to see if she was the Kanima first. Confused, Jackson instantly went to Scott and Stiles to ask them what a Kanima was in hopes of figuring out what was going on.
In chemistry, they're doing an experiment which required them to rotate partners, Erica starts with Scott, he asks her to hold off on whatever it is they plan on doing, Erica leaned in on him and realized something, she tells Scott they she smelled Allison all over him, even though they pretended to break up. She began to flirt with him, saying that she'd be "wanting him all the time," implying she's attracted to him, but Scott turns her down. Before it can go any further, the bell is rung and they have to switch partners. Erica is paired with Allison next.
She begins to mess with Allison's emotions, telling her that she and Scott would never last, Allison attempts to get back at her but Erica then puts her claws on Allison's leg, teasing with the concept of a girl fight in the lab and that it would be "hot." She, Isaac and Derek soon discover that Lydia passed the test and therefore, must be the Kanima, she and Isaac searches the school for her but then they learn that she's been taken to Scott's house. Erica enters Scott's room, she and Allison get into another confrontation, Allison shoots an arrow at Erica but she catches it; however, its covered in Kanima venom, which paralyzed Erica. She was thrown out of Scott's house and taken back to Railway Depot by Boyd while Derek pursued the Kanima, who turned out to be Jackson after all but he and his Betas had no idea of this.
In Restraint, Derek told Erica and Isaac to get closer to Scott and Stilesbecause they may need their help in stopping the Kanima. Isaac reminded Derek that the next full moon was getting closer and that he promised to teach his Betas how to control their transformations, only for Derek to tell him he didn't have enough time. Isaac suggested they forget the Kanima but Derek impatiently yelled that they couldn't and showed his concern about the way the Kanima looked at Gerard Argent the previous episode, meaning the Argent Family patriarch had some plans with the Kanima.
At school, Erica heard Stiles asking Lydia about Jackson's parents, which seemed to pick up Erica's interest. After cornering Stiles, she demanded to know why he was questioning Lydia about Jackson's real parents and Stiles advised her to hide her claws from the surveillance cameras to avoid being exposed as supernatural. Stiles playfully invited her to play Catwoman and Batman, before she revealed that Jackson's parents were buried in Beacon Hills Cemetery. She refused to tell Stiles how she knew what happened to Jackson's parents until he told her why he wanted to know but he eventually did not have to do it because after connecting the death of Jackson's biological parents with the Kanima's legend, Erica realized that Jackson was the Kanima all along, even though he was paralyzed by his own venom while in human form. Stiles attempted to stop her from telling Derek about Jackson because he warned her that just because she had an "Alpha Bite makeover", it didn't mean she could go out there and destroy other people's lives but Erica fired back that others had destroyed her life prior to her transformation into a Werewolf. She informed Stiles that she used to have a huge crush on him but he never noticed even once because of his crush on Lydia. They noticed water coming out the locker room's floor and, not long after that, Scott and Jacksom came out, fighting each other. Erica restrained Jackson while Stiles did the same with Scott just as Mr. Harris showed up.
As a result of the brawl between Jackson and Scott, Mr. Harris gave all of them detention in the library. After Jackson, who was suffering side-effects from his transformation into a Kanima, left the library for a few moments, Scott and Stiles approached Erica and demanded to know how she knew Jackson's parents and how they died, leading Erica to tell them it was a car accident and her father was the insurance investigator, who seemed to make many comments about Jackson getting a huge settlement when he turned eighteen. She gained access to her father's mail box and managed to find the report about the death of Jackson's biological parents, which said Jackson was born with C-section but the report was considered "inconclusive", suggesting Jackson's parents could have been murdered, which fits in the Kanima's reputation of killing murderers but this was never proven to be the case.
They were all tasked with re-shelving the books, at which time Jackson began to transform and destroy the library, paralyzing both Matt and Erica in the process. After Jackson left the library and left them a message from his master, Scott and Stiles realized Erica was having a seizure as a result of the Kanima Venom and took her back to Railway Depot, where Derek broke her arm in order to re-trigger her healing ability but it was really painful and Erica called Stiles a "good Batman". After seeing how dangerous Jackson is, Scott agreed to join the Hale Pack until they saved him but insisted they do things his own way.
In Raving, Scott and Stiles figured out who was going to be Jackson's next target, Erica and Isaac were given the task with the job to drug him at the rave, where he would be killing Kara Simmons. Jackson was seen walking towards Kara to kill her as per his master's orders but Erica and Isaac found him and began dancing with Jackson as a distraction, which would allow Isaac could inject him with a syringe of ketamine. However, Jackson and his master anticipated their plan and the Kanima Master had Jackson stab both Erica and Isaac with his claws, muttering "He belongs to me." The two Betas managed to pull themselves up and subdue Jackson so they could take him into an empty room, where they were soon joined by Stiles, who began interrogating Jackson, whose master used his connection to him to speak to the three through his mouth, about the murders that he committed the last few weeks.
Jackson's master explained to them that he had been using Jackson to kill the people who "murdered" him but Stiles, Erica and Isaac did not seem to understand this but their confusion turned to shock and fear when Jackson began to overcome the effects of the ketamine and began to transform into his Kanima form. Since the whole vial of ketamine was used, Stiles, Isaac and Erica left the room and blocked the door with their bodies to stop Jackson from escaping but Jackson, in full-Kanima form, managed to escape by running through the wall and ultimately killed Kara. Erica and Isaac met with Derek outside but they couldn't leave due to the Mountain Ash barrier that Stiles created around the building, but they were able to cross it when Stiles broke it so Derek could rescue Scott, who was poisoned with Wolfsbane by Victoria Argent.
In Party Guessed, Derek was seen opening up a trunk full of chains and restraints to lock the young Betas up during the full moon, which would be Erica and Boyd's first but Isaac's second. Isaac noticed a triple spiral in the trunk and asked what symbol it was. Boyd explained that the triskelion was used to represent different things: past-present-future or mother-father-child; Derek, visibly impressed and proud by Boyd's intellect, explained that, for their species, the triskelion served as a reminder that they could always rise to one rank or fall to another, with Betas becoming Alphas and Alphas sacrificing their powers to return to Betas or Omegas. Isaac inquired about Scott being a lone wolf but Derek assured them that Scott finally joined their side and he was currently keeping an eye on Jackson and his movements to make sure that nobody innocent got hurt or even killed by him. He warned them that their lycanthropy did not come without consequences as they would be overwhelmed by the urge to rip apart anything in sight that night. Erica remarked that she would be ready for such case after she told them that she has had her period last week but her relief turned to slight concern when Derek pulled out a headband with spikes embedded within it and informed Erica that she would be the one to wear it.
As the full moon was getting closr, Erica, Isaac, and Boyd were being chained up by Derek inside the subway car. Isaac asked why Erica get to wear the headband with spikes, and Derek replied that she would be able to withstand more pain than Boyd and Isaac before offering Isaac one for him as well, but Isaac refused. She was held in place as Derek screwed the headband on, but it caused her a great deal of pain and suffering. When the full moon rose, Erica fully-shifted into her wolf form and eventually broke free of her restraints before she and Boyd started attacking Derek. After Isaac found an "anchor" to his humanity thanks to Derek's guidance, Derek and Isaac were able to chain Boyd and Erica back up.
In Battlefield, she and Boyd were walking through the woods, as she reminded Boyd that Derek told them to be back before the sun rose. They stopped in their tracks after a howl was heard and wondered if there were any other Werewolves out there as the howl did not sound like Derek's. They heard multiple more howls coming from several directions, concerning them that they rushed back to Derek. They soon arrived at the Hale House, where they informed Derek they would be leaving Beacon Hills during the lacrosse game but they said it wasn't like they wanted to do so. Erica told Derek that she had turned sixteen years old just a month ago and was intent in obtaining her driver's license but her death would be the only thing that could keep her from getting it. Though Derek reluctntly admitted that he did not warn them properly of the disadvantages of being a Werewolf, he reminded them that he had taught them that they needed a pack to survive and there was no pack without an Alpha. They expressed their beliefs that there was another pack in or near Beacon Hills because of the howling they heard in the woods. Derek scoffed and explained to them the "Beau Geste effect", it's when one wolf can modulate its howls to sound like a dozen or more, but Erica and Boyd showed no concern and made it clear that their minds were made up and they left anyway.
When night fell, Derek proved to be right as the howling that they heard was actually being done by The Argents using a recording. Fortunately, Erica and Boyd were hidden bhind a tree and realized they were lured into a trap.
When they were found, the two ran as fast as they could through the forest with the Argent Hunters, who were on ATV's, on their tail. At some point, Erica got shot in the leg with an arrow by Argent but she showed no fear as the young Huntress prepared to fire another arrow. Boyd returned and caught the arrow fired at Erica and Allison began shooting him as well. She continued to fire arrows at Boyd's chest and abdomen, out of anger and bloodlust as she blamed the Betas and Derek for her mother's death but Argent utlimately saved them by shooting Allison's bow, before they were taken back to the Argents' house.
In Master Plan, Erica and Boyd were tied to the ceiling of the basement of the Argent House with their mouths taped over. Gerard had captured Stiles as well and threw him into the basement, where he found the young Betas. Stiles tried to take the wires from around Erica's wrist but it shocked him and her, just as Gerard came in and explained to Stiles that Erica and Boyd were trying to tell him that it was electrified. Since their instinct to protect their Alpha was too strong to give away any information, it was worthless to torture them before he began beating Stiles up. Later on, Argent entered the basement and told them that his family had been hunting for a very long time, gaining a great deal of knowledge about Werewolves and how a certain level of electrical current can keep them from transforming, another level prevented them from healing, and one of the highest levels could reduce their strength to that of a human. He further explained that the lines between natural and supernatural started to blur, and sometimes you could be surprised by which side of the line you end up on. Having seen how cruel and monstrous his father truly was after seeing him corrupt his daughter Allison, Argent released the two and allowed them to flee. After Gerard had been defeated and Jackson was saved and turned into a Werewolf, Erica and Boyd were seen running through the woods but they stopped momentarily to catch their breaths, when they were suddenly surrounded by a pack of Werewolves.
In Tattoo, Derek revealed that Erica and Boyd had been missing for four months, and he, Isaac, and Peter had been looking for them this whole time upon learning they had been captured by the Alpha Pack.
In Chaos Rising, Isaac Lahey, after being put into a trance to get his repressed memories by Deucalion back, revealed to Derek, Scott, Stiles and Deaton that he found Erica's lifeless body in a closet of the First National Bank, where Boyd, Erica and Derek's long-lost sister Cora Hale were being held hostage by The Alpha Pack, during his brief time as a hostage of the Alphas. This was later confirmed when Allison found her dead body in that same storage closet when hiding from the Alphas after breaking into the bank.
In Fireflies, Derek was shown to have found Erica's body and brought it back to show it to Scott and Allison as he stared at her body with a look of distraught.
In Currents, Kali, Ethan, and Aiden forced Derek to kill Boyd and steal his powers. Derek saw through the memories of his dying Beta a day back when Erica was still alive and she and Boyd were in the bank vault. She asked Boyd what he thought that would happen to them during the lunar eclipse, and she hoped that it would make them stronger. She repeated her sentence one more time for Kali, who was watching over them and was about to leave the vault, to hear it. Erica flashed her golden Werewolf eyes at Kali and she attacked the Alpha, only to be quickly defeated and killed during the confrontation, and managed to whisper Boyd's name with her last breath as she tried to reach him before she perished in front of him.