Deadpool himself could be considered the main antagonist in this case, as he is the one who is set on killing Peter Parker. His unpredictable and violent nature makes him a formidable foe.
In the fanfiction, it might be that there's a misunderstanding between Deadpool and Peter Parker. Deadpool could think Peter has done something really bad, like endanger the lives of other mutants, when in fact it's a false perception.
One common theme is the clash of personalities. Peter is more of a by - the - book hero with a strong moral code, while Deadpool is chaotic and often breaks the rules. Their interactions based on these differences are often explored.
One interesting fanfiction could be where Peter Parker and Deadpool team up to take on a powerful new villain in New York. They have very different styles, with Peter being more of the traditional hero and Deadpool being, well, Deadpool. Their banter throughout the story as they try to figure out how to work together would be really engaging.
Well, Deadpool might crack a lot of jokes and make Peter Parker super confused. He could also try to team up with Peter to fight some villains, but his crazy methods would probably drive Peter nuts.
One common theme is the clash of personalities. Peter is more reserved and responsible while Deadpool is wild and unpredictable. Their interactions often revolve around this contrast.
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.
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.
You can try websites like Archive of Our Own (AO3). It has a vast collection of fanfictions, and you can easily search for Peter Parker and Deadpool related stories using the search bar. There are filters available too, so you can narrow down your search based on ratings, word count, etc.
One great Peter Parker and Deadpool fanfiction is 'The Unlikely Team - Up'. It has a really interesting plot where they are forced to work together against a common enemy. The author does a great job of capturing their different personalities, with Peter's sense of responsibility and Deadpool's wackiness.