Kate was raised to hunt werewolves and taught her families 400 year history but she had no respect for the code by which the hunters were supposed to operate.
When she was a young woman, she conspired with a number of people to burn down Hale House with a large number of the family locked inside. She got away with the murders for six years. When Peter Hale recovered from his injuries he came hunting for the arson conspirators.
Peter tore out her throat with a deep scratch but Kate's body began to heal. Suspecting that the scratch of an Alpha would result in transformation, Mexican Hunter Araya Calavera came to Beacon Hills to check. She found Kate's body was healing and transforming and took her back to Mexico.
Kate fully recovered as a Werejaguar, faked suicide, and escaped. She made it to the temple of Mexican jaguar god Tezcatlipoca in a place known as La Iglesia. She was aided by the berserkers there and learned she could control them. She became known as "La Loba: The Bone Woman" and learned from Peter Hale that she also had the ability to create berserkers.
She blamed Scott McCall for the death of her niece Allison and for what she termed "the decimation" of the Argent family. While her plan to kill Scott failed, she managed to escape capture and is currently on the run from the Calaveras and her brother Chris.
Her grave remains in Beacon Hills Cemetery. The gravestone reads "KATHERINE ARGENT 1983-2011"
Throughout Season 1, Kate pushed Allison to learn more about her family and their mission to hunt werewolves.
In The Tell, she gave Allison a silver pendant featuring a wolf. In Heart Monitor, she directed her to the French legend of La Bête du Gévaudan and the connection between the beast in the story and the Argent family. In Lunatic, Kate taught Allison to use a Taser gun.
Kate was fearless and possibly sociopathic when it came to dealing with werewolves.
During a later confrontation with Derek in The Tell she seemed to enjoy taunting and torturing him before trying to kill him. She constantly pushed Chris Argent to act against The Alpha while her brother urged restraint as they gather more information.
The character’s dialogue was rife with sexual innuendo. She made suggestive comments to Derek while torturing him and teased Scott during the family dinner in Magic Bullet.
In Formality, Kate told Allison the truth about werewolves as she tortured Derek for information in hope of finding the Alpha and the other Beta. Kate and Derek were involved in a relationship similar to that of Scott and Allison. Kate told him the sex was great but that she was just using him to find and kill the rest of his pack.
In the season finale, Code Breaker, Peter Hale held Kate hostage and threatened to kill Allison unless Kate apologizes for what she had done to his family. Saying Kate’s apology didn’t ring true, Peter ripped out her throat. Later her corpse is seen by the police who discover the necklace around her neck. With this being done, she is blamed for the Hale House burning down, and the murders of her co-conspirators.
In the winter premiere, Kate returns as part of Allison's nightmares and hallucinations. Kate seems to be an ultra-violent and malevolent side-effect of Allison's "death" (see Lunar Ellipse) leaving the teen visibly shaken after each encounter. (read more...)
She appears in Allison's hallucinations again but this time as a "werewolf surgeon" who starts eating her innards with other werewolf doctors. (read more...)
Though she was dead at the end of Season 1 and buried at the beginning of Season 2, it appears Kate has returned to Beacon Hills as some, heretofore unseen, supernatural creature known as "La Loba" to the Spanish speaking hunters chasing her. (read more...)
Kate's body had begun to heal after her "death" in Season 1. The Calavera's took her to Mexico where she fully recovered and faked a suicide to escape. She is seen briefly in what appears to be an Aztec temple, guarding a sealed tomb where Derek is tied up. (read more...)
Kate has trouble controlling her new shapeshifting abilities which leads to death a of a gas station attendant. She convinces young Derek to take her to his family's vault because she believes there's something there that can help her control shift. (read more...)
Four weeks ago Kate got a mixtape explaining the Hale's Triskelion. After she finds out the tape lied about the "sacred object," she goes in search of The Benefactor, killing a number of assassins seeking information. She fights her brother but doesn't let the Berserkers kill him. Peter comes to her with an offer. (read more...)
Kate brings the Berserkers to the hospital in hopes of stealing Scott's body. She calls off the attack when she realizes that he's not really dead. (read more...)
Kate and Peter discuss what to do next now the Dead Pool has stopped. (read more...)
Kate attacks and kidnaps Scott and Kira admitting she doesn't understand how an ancient and powerful family like the Argents was laid low by a teenage boy. She appears to be turning Scott into a berserker. (read more...)
Kate tests out berserker Scott's loyalty by having him attack Kira. She takes on her brother and a whole team of Araya Calavera's hunters. She is finally beaten by a fully transformed Derek Hale and shot with a Yellow Wolfsbane bullet by Chris Argent. She manages to escape. (read more...)
- “You know how every family has its secrets? Ours are a little different.” — Kate to Allison in Co-Captain.
- “You don't have to be psychotic to be a killer. You just... need a reason and even then, sometimes... You can surprise yourself.” — Kate to Allison at the Hale House in Wolf's Bane.
- “I don't know whether to kill it or lick it.” — Kate to Derek in The Tell.
- “Sweetheart, there are werewolves running around in the world. Everything's a joke to me. How else do you think I stay sane?” — Kate to Allison in Formality.