The character of Thanos gets defeated in the comics by a variety of factors and characters. It could be a powerful solo hero or a coordinated attack from a group of them.
Well, there are multiple instances and circumstances. It could be a combination of heroes or a single powerful character, depending on the specific comic arc.
Yes, there are likely fanfictions out there where Tony kills Thanos. The Marvel universe has a huge fan base, and fans often create alternative storylines. Some might explore this scenario to give a different take on the Infinity War and Endgame stories.
One consequence could be that Peter Quill Parker becomes a hero. People all over the universe might look up to him. But he may also face some jealousy or envy from other powerful beings.
Peter could use his agility. Since he's super - agile, he can dodge Thanos' attacks easily. Then, when Thanos is off - guard, Peter can strike. For instance, he can web up Thanos' hands so he can't use the Infinity Gauntlet properly.
In this fanfiction plot, perhaps Thanos' actions in the Marvel universe start to affect Naruto's world. Naruto then sets out to find the source of the disturbance. When he encounters Thanos, he is initially outmatched. But as the story progresses, Naruto befriends some of the Marvel heroes who teach him about Thanos' powers. Naruto then trains hard, combines his ninja skills with new knowledge, and in a final epic battle, he manages to kill Thanos. The story could also include Naruto's internal struggle as he is in a completely different world with different rules and enemies.
In a Naruto kills Thanos fanfiction, Naruto's sealing techniques could play a major role. He could use sealing jutsu to seal away Thanos' powers or even Thanos himself. Naruto has experience in dealing with powerful foes and sealing them away. Also, Naruto has the ability to sense danger and react quickly. Thanos, on the other hand, may underestimate Naruto at first. By the time he realizes Naruto's true strength, it could be too late for him.
One possible plot twist could be that Peter uses his intelligence rather than just his powers to defeat Thanos. Maybe he discovers a weakness in Thanos' armor or a flaw in his plan that no one else has noticed. For example, he could find out that Thanos' Infinity Gauntlet has a time - limited recharge period for its powerful snaps, and he uses this knowledge to his advantage at a crucial moment.
In a 'Tony kills Thanos' fanfiction, the plot could start with Tony being haunted by his previous failures against Thanos. He decides to go on a solo mission to study Thanos more closely. He discovers a way to disrupt Thanos' connection to the Infinity Stones. With this knowledge, he devises a plan. He lures Thanos into a trap where he has set up a device that can nullify the power of the Stones. Then, in a tense battle, Tony uses his own advanced technology and combat skills to fight Thanos without the Stones' advantage and finally manages to kill him. This could be a story of redemption for Tony, showing his determination and ingenuity in the face of seemingly insurmountable odds.
One possible plot could be that Peter Parker discovers a new power within himself that gives him the edge to take on Thanos. Maybe it's a power related to the Time Stone that he manages to manipulate in a way that Thanos can't counter. He could use this power to outwit Thanos in a battle and finally deliver the killing blow.