Scarlett Johansson could be a great choice. She has proven her ability to play strong and complex female characters. Her experience in action movies would also be beneficial in portraying the more physical aspects of Female Venom.
Yes, there are quite a few. You can start by looking on fanfiction.net or Archive of Our Own. There are many talented writers who explore the concept of Peter Parker being Venom in different ways. Some might focus on how he copes with the new powers and the dark side of Venom, while others could be more about the unique adventures he has as Venom - Peter Parker.
Another way Peter could become Venom in fanfiction is through a magical or mystical event. Maybe there's a spell gone wrong that links Peter to the Venom symbiote. This would give the story a different kind of feel, with Peter having to deal not only with the physical changes but also the magical implications. He might seek help from Doctor Strange or other magic - using characters in the Marvel universe to understand and control his new state.
Mary Jane could be a great addition. She could be the one who helps Peter deal with the emotional turmoil of having Venom as part of him. Another good character is Ned. He could be the tech - support, trying to find ways to control or enhance Venom's powers. And of course, there's Doctor Octopus. He could be a great villain in the fanfiction, either trying to steal Venom's powers or team up with it against Peter.
At first, it would be really rocky. Peter would be very wary of Venom given their past encounters. But as Venom shows his more caring side in the adoption, Peter would start to trust him a bit. They'd have to learn to communicate, which would be difficult because of Venom's different way of thinking.
One great peter parker venom fanfiction is 'The Bond of Symbiote and Spider'. In this story, it explores how Peter Parker initially struggles with the new power and presence of the Venom symbiote. It shows his moral dilemmas as the symbiote tries to influence his actions, making for a really engaging read.
In a fanfiction where Peter Parker becomes Venom, it could be due to a scientific experiment gone wrong. Maybe Oscorp was working on a new symbiote project, and Peter, being the curious and heroic type, gets involved accidentally. The transformation would change his personality, making him more aggressive at first as he struggles to control the new power. He might initially see the symbiote as a curse but later learn to use it for good, in a different way than he does with his Spider - powers.
Perhaps the plot involves Venom sensing that Peter has a pure heart despite their initial differences. Venom adopts Peter because he realizes Peter is alone in the world after some tragic event in the fanfiction. Venom then tries to teach Peter how to use his powers in a more aggressive way, which Peter is initially hesitant about but later comes to understand. This could lead to Peter becoming a more formidable Spider - Man with Venom's influence.
Often, other symbiotes can be the main antagonists. For instance, Venom himself might see Anti - Venom (Peter) as a threat and constantly try to attack him. Venom could be jealous of the power that Anti - Venom has or simply view Peter as an enemy because of the different nature of their symbiotic relationships.
One idea could be that the Female Venom forms an unexpected alliance with Peter Parker. Maybe she initially has her own motives but as they interact more, she starts to see the good in Peter and his mission to protect the city. They could team up to take on a new super - villain that neither could face alone.
In some versions, he might stumble upon the symbiote in a hidden lab where it was being studied. Maybe some scientists were trying to weaponize it and Peter, through his spider - sense, detects its presence and manages to bond with it again.