Maybe in the fanfiction, Natasha betrays Tony because she has been brainwashed by an enemy organization. They manipulate her mind to turn against Tony and his Avengers team. This could lead to a lot of action and drama as Tony tries to figure out what's wrong with her and how to save her.
It could be a new villain that we haven't seen in the original Marvel universe. This villain might be able to manipulate Natasha's emotions and loyalty, making her betray Tony. For example, a powerful sorcerer who uses dark magic to control her.
One interesting storyline could be them teaming up on a top - secret mission. They have different skillsets, Natasha with her combat and espionage skills, and Tony Dinozzo with his investigative and street - smart abilities. Their interactions during the mission, like initial clashes due to different working styles and then gradually growing to respect each other, can make for a great plot. Maybe they discover a conspiracy that reaches far beyond what they initially thought, and they have to rely on each other to expose it.
One possible reason could be that Tony has some pre - existing biases. Maybe he has a set idea of the type of person he wants on his team and Natasha doesn't fit that mold in his mind. For example, if he's looking for someone with a more technical background and Natasha's skills seem more combat - oriented to him at first glance.
One possible storyline could be Tony helping Peter deal with school bullies. Since Tony is now his guardian, he uses his influence and resources to ensure Peter has a safe and positive school environment. For example, he might set up a scholarship fund in Peter's school for anti - bullying programs.
One possible storyline could be that Tony Dinozzo is facing extreme pressure at work, like constantly being in dangerous situations and feeling responsible for the safety of his team. This stress builds up over time and he starts to think that his death would relieve everyone of the burden he believes he is. Another could be related to personal loss, such as the death of a close friend or family member, which makes him fall into a deep depression and consider suicide.
She would likely become angry. Natasha is a strong character, and being betrayed would stir up her fury. She might start planning her revenge, using her skills and intelligence to get back at Percy. Maybe she'll try to expose his true motives to others in their world or group.
A possible plotline could be them having to keep their marriage a secret from the world. Maybe because of Tony's business rivals or Natasha's undercover work. They would have to navigate their relationship while hiding it from everyone, which could lead to some really tense and exciting moments.
Another storyline could be that they get involved in training the next generation of superheroes or tech - savvy individuals. They realize the importance of passing on their knowledge and skills. Tony could teach about advanced engineering and Pepper could offer her business and leadership expertise. This would be their way of ensuring a better future for the world.
One possible storyline could be Jarvis struggling to live up to Tony's legacy. He might feel pressured to be as brilliant as his father in the field of technology. Another could be Jarvis discovering a new technology that Tony had been working on secretly and continuing his father's work. Maybe there could be a storyline where Jarvis has to defend Stark Industries from a new threat using his own unique skills that he developed under Tony's guidance.
One possible storyline could be that the Avengers are under some form of mind control. Maybe a powerful villain has manipulated them into believing Tony is a threat to the world. So, they start to target him, causing both physical and emotional harm. For example, they might break into his workshop and destroy his latest inventions, which are not only his creations but also his passion.