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 the fanfiction, Peter Quill Parker might have some new powers or gadgets that give him the edge. He could have studied Thanos' fighting patterns and found a way to counter them. Also, his quick thinking and ability to improvise in tough situations would play a big role. He might even use his charm to get close to Thanos and then strike when he least expects it.
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 would probably be scared at first. He's just a kid, after all, and being kidnapped by a powerful being like Thanos is terrifying. But he would also be defiant. He has a strong sense of responsibility, so he might try to find a way to escape on his own.
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.
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.
Peter's character could become more hardened. Killing Thanos, a powerful and feared villain, would weigh heavily on him. He might struggle with the moral implications of taking a life, even if it was to save the universe. This could lead to a more somber and introspective Peter.
In these fanfictions, Peter may develop a stronger sense of leadership. When Midtown is in danger and he's fighting Thanos, he has to take charge. He might start to give orders to his friends or come up with strategies that not only help him in the fight but also show his growth as a leader. For example, he could be coordinating the efforts of other superheroes or even normal people in Midtown to fight Thanos together. This is a big step from just being the friendly neighborhood Spider - Man.
In a Thanos and Peter Parker fanfiction, it could be set in an alternate universe where Thanos has already won. Peter Parker is one of the few remaining heroes. He has to go undercover and try to find a way to reverse what Thanos has done. Peter uses his street - smart skills from Queens to blend in among the survivors and slowly gather information about Thanos' weaknesses. He might even form an unlikely alliance with some of Thanos' minions who have second thoughts about their master's actions.
One key element is the power dynamic. Thanos is extremely powerful, with the Infinity Stones, while Peter has his spider - abilities. So, how Peter overcomes or at least contends with Thanos' power is a big part. Another element is the moral conflict. Thanos has his own warped sense of right and wrong, and Peter has his strong moral compass. Writers often explore how these two different viewpoints clash.
Thanos killed Peter Quill in a rather brutal way. He used his immense power and some sort of cosmic energy blast to take him down.