So I'm John Lawrence's son

The Impala roared down the sunny streets of Reseda, the hot asphalt rippling in the afternoon sun. Jack's grip on the steering wheel was white-knuckled, his jaw clenched. The image of Sam and Robby, entwined and oblivious to the world, burned into his mind like acid. 

He jerked the car to a stop in front of the LaRusso house, the imposing, familiar mansion now a monument to his own stupidity. Amanda, ever gracious, opened the door with a welcoming smile. 

"Jack! What a nice surprise!" she exclaimed, genuinely happy to see him. "Come in, honey. Sam and Robby are back there, training." Daniel had gone out for a while and left the two to train alone. 

He nodded, crossing the house like an automaton. In the backyard, the scene that awaited him confirmed his worst fears. Sam, with a flushed face and hair damp with sweat, was on top of Robby, who looked at her adoringly. Roby wasted no time and kissed her. Samantha was surprised by the kiss, but she didn't pull away from it, she accepted it. The frustration of not being with Jack and losing him to Moon made her accept Roby, who was showing that he liked her...

Jack saw this and froze there, everything he had come to do there had lost its meaning, anger consumed him, he almost shouted at her, but he remembered: "He had nothing to do with Sam other than being her friend, memories of Samantha came back to him, she practically confessed herself to him several times and he pretended not to understand, not accepting that it was true, he thought that everything would continue as always with her always liking him, but it wasn't like that, life goes on and seeing this in front of him hurt him, he turned around and left.

But what Jack didn't notice, blinded by anger and disappointment, was Sam's gaze. She saw his back coming out of the back of the house, she recognized him immediately. Surprise and regret took over her face, she stopped kissing Roby and got off of him. 

Roby was confused as to why she stopped, everything seemed to be going well."

Meanwhile, with Jack, anger consumed him, a wave of frustration and self-loathing. He turned on his heel, his vision blurry, and left the house without a word. Amanda called after him, confused, but he didn't look back. 

Amanda went to tell Samantha that Jack had come to talk to her about something, but had simply left. 

The beach was his refuge, the place where the relentless waves and the relentless wind washed away his sorrows. He walked across the cold sand, his feet sinking with each step, until he found a secluded rock. There, with the ocean roaring in the background, his thoughts of what he had seen awakened him to something that had been gnawing at him for a long time. Bob's words of regret had not only influenced his mother back then, but by that day, something in him had changed. He had let the child he once was enter his being, and it had taken over him completely, but now he understood that being a child no longer helped anyone, least of all him. From that day on, that stupid and sweet boy died, his older self returned, that guy from the streets, the boy who at 8 years old stole, fought to survive, suffered from cold in the middle of storms, he would go back to being that person, that guy there was his true self, not this sissy who is ashamed to talk to women, who has no attitudes to show who his true self was, who let another girl take the reins of everything, enough of all that. 

The memory of Moon, radiant and in love, invaded his thoughts. She wanted him, that was undeniable. And maybe, just maybe, it was time to give her, himself, a chance. Why not? She was hot, and she also liked him, why not give it all a chance? 

Some time later 

Sam was tormenting herself. She didn't understand why Jack had come to her house that day, her thoughts trying to understand why, maybe he had come to declare himself, and that was the worst thought that went through her head, if that was true, everything was over right there, everything she could have with him was over, and it hadn't even started and it was already over. But Samantha also blamed Jack, if that was true, he didn't understand all her hints or maybe he knew everything but didn't care about her feelings, that hurt her more than she thought. The kiss Moon gave him that day at the tournament and at the costume party where she saw them making out confirmed that, if he didn't really want her, he would have told her so and ended it all. 

To make matters worse, Moon never missed an opportunity to rub her happiness in Sam's face. Her social media was a parade of photos and videos with Jack, always with cheesy captions and passionate declarations. Sam felt humiliated, rejected, and jealous. She wouldn't let this get to her. If that was what Jack wanted, that was fine. She would move on too. She wouldn't be the idiot who would suffer for him. 

At the Cobra Kai dojo, Jack's transformation was evident. His strikes, once filled with anger and frustration, were now precise, controlled, and deadly. He trained with a cold fury, the determination of a predator. 

Johnny Lawrence watched, impressed. Jack was a diamond in the rough, a natural talent that only needed polishing. And Johnny, with his experience and discipline, would be the craftsman who would shape him. 

"You've got potential, kid," Johnny said after practice, his voice hoarse. "But you need to learn to control your anger. It can be your greatest strength, but it can also be your greatest weakness." 

Jack nodded, absorbing his father's words "Who didn't yet know that Jack was his son", He knew Johnny was right. Anger drove him, but it also blinded him. He needed to find the balance, the harmony between strength and control. 

Over the next few days, Jack dedicated himself to training with great dedication. He learned to channel his anger, to use it to his advantage, to transform it into a powerful weapon. He became a Cobra Kai in body and soul, ready to face any challenge. 

With Moon, he found unexpected joy. She was lighthearted, fun, and made him forget his troubles. They laughed together, explored the city, and supported each other through difficult times. Jack wasn't in love with Moon, but he liked her, and that was enough for now. 

Jack Sullivan, the lost and insecure boy, had become a Cobra Kai. He was strong, confident, and determined to forge his own path. The future was uncertain, but one thing was certain: Jack would not let himself be beaten. From that moment on, he would fight to become stronger every day.