Warning: SPOILERS for Cobra Kai season 3.
In Cobra Kai season 3, John Kreese (Martin Kove) goes out of his way to help Tory Nichols (Peyton List) in a manner that's uncharacteristic for the sadistic Cobra Kai sensei. Cobra Kai season 3 picks up two weeks after the ultraviolent West Valley High brawl that Tory started in order to get revenge on her arch-enemy, Samantha LaRusso (Mary Mouser). Tory did pay a price for the mayhem she caused, which resulted in Miguel Diaz (Xolo Mariduena) hospitalized in a coma, but Kreese was an unexpected knight in shining armor for Tory.
When Tory joined the black-and-yellow dojo in season 2, Kreese doubted that an attractive girl like her was Cobra Kai material but Nichols quickly proved she was aggressive enough when she went toe-to-toe with Miguel, Sensei Johnny Lawrence's (William Zabka) top student and the reigning All Valley Under 18 Karate Champion. Tory fit right in with Cobra Kai and she bought into the dojo's "strike first" philosophy; Nichols also felt no particular loyalty to Johnny, unlike Miguel, and she had no trouble with Kreese stealing the Cobra Kai, reinstating his "no mercy" policy, and demanding that his students become even more violent. The fact that Tory started the West Valley High fight and planned to injure, if not even kill, Samantha LaRusso, proved that she was exactly the kind of student Kreese was looking for all along, although she and the other Cobra Kai losing the fight to Miyagi-Do was an unacceptable result. Still, Tory was at the practice led by Kreese at the end of Cobra Kai season 2 but she left the dojo soon after.
Cobra Kai season 3 revealed that West Valley High expelled Tory but she escaped juvenile detention because she's the sole caretaker of her sick mother and her little brother. However, because she's the family breadwinner, Tory has to work two jobs to pay the rent as she tries to earn her G.E.D. which leaves her no time to train at the Cobra Kai dojo. Yet, remarkably, Kreese came to Tory's rescue; he offered to let Nichols train for free - something Kreese has never done for anyone else in Karate Kid/Cobra Kai history. The sensei even handled Tory's problem closest to home when he beat up and threatened to cut Tory's dirtbag landlord's fingers off if he didn't stop harassing the teenage girl. By the time Kreese was done helping Tory, she was able to take her spot in Cobra Kai once again. These appear to be highly unusual acts of generosity for Kreese, but they really are just about fulfilling his private agenda as opposed to his genuinely caring about Tory.
Kreese prizes Tory because he recognizes her as a "born fighter", which he saw proven by the way she steps up to care for her family with no support. But given Kreese's backstory, which unfolded in flashbacks during Cobra Kai season 3, John may also see something of Betsy (Emily Marie Palmer), the only woman Kreese ever loved who died while he was in Vietnam, in Tory. However, in terms of karate, Tory is the most gifted natural student Johnny recruited in the first two Cobra Kai seasons. And, in Kreese's eyes, Tory is the equal of, if not better than, Miguel, who is both injured and too loyal to Johnny anyway. By helping Tory, Kreese transactionally earned her loyalty, and she takes Diaz's place as his top student because Kreese has never been satisfied with Hawk (Jacob Bertrand), no matter how hard the mohawked fanatic tries to be the dojo's top snake.
Ultimately, Kreese is disappointed that Cobra Kai lost at West Valley High but he's looking to rebuild his roster, get rid of the dead weight Johnny brought in, and pack his dojo with the strongest fighters who are loyal to him. Tory is a top tier Cobra Kai as far as Kreese is concerned. As old fashioned as Kreese is, he recognizes a kindred spirit with a chip on her shoulder and a grudge against the world in Tory. In Kreese's eyes, Nichols isn't one of the "snowflakes" he believes the rest of the kids of her generation are, and she has shown sociopathic tendencies. Plus, Tory has unfinished business with and hatred for Sam LaRusso, and having a score to settle with the LaRusso family is something else John Kreese completely understands and supports - and will use to further his own ends.