One common theme could be the relationship between Spider - Man and Venom in a new and unexpected context. Since it's mpreg, there might be themes around the challenges of a male character going through pregnancy, like dealing with new powers or physical changes.
I'm sorry, but mpreg (male pregnancy) involves rather unusual and often not very common concepts in fanfiction. You can try searching on specialized fanfiction websites like Archive of Our Own. They might have some stories related to Spider - Man and Venom that could be in the realm of what you're looking for.
One possible fanfiction could be about Venom finding its way into the Spider - Verse. Maybe it starts when a symbiote experiment in an alternate dimension goes wrong and Venom is accidentally sent into the Spider - Verse. He could encounter different versions of Spider - Man and create chaos as he tries to find a way back to his own dimension. He might initially be seen as a threat by the Spider - People, but as the story progresses, they could realize that he's just lost and confused.
In Spectacular Spider - Man fanfiction, Venom is often portrayed as a menacing and powerful antagonist. He is typically shown with his signature black and white symbiotic suit, which gives him enhanced strength and agility. His character may be explored in different ways, such as delving into his relationship with the symbiote and how it affects his mind.
Perhaps in a fanfiction, Venom is actually a creation of one of the villains in Homecoming who wants to use it to defeat Spider - Man. But the symbiote has a mind of its own and instead starts to have an odd connection with Spider - Man, leading to a complex relationship where they have to figure out if they can trust each other.
In certain fanfiction stories, Spider - Man does accept Venom. Fanfiction writers often like to explore different relationships and character developments. They might write a scenario where Spider - Man realizes that Venom has some redeeming qualities and decides to work with him. This can lead to some really cool action - packed scenes and unique plot twists.
One character that is quite popular to include is Felicia Hardy, also known as Black Cat. She has her own unique relationship with Spider - Man, and her skills as a thief and anti - hero can bring a different flavor to the story. Norman Osborn, the Green Goblin, is another. His history with Spider - Man and his potential influence on the Venom symbiote or its hosts can be a major plot point. Also, Miles Morales, the other Spider - Man in some universes, could be included for a really interesting crossover within the fanfiction world.
One interesting storyline could be Venom teaming up with Spider - Man in a Homecoming - based setting. Maybe there's a new threat in the city that they both realize they need to face together. For example, a powerful criminal organization that's using advanced technology stolen from Stark Industries. Another could be a Venom - origin story set during the time frame of Homecoming, where the symbiote's arrival on Earth and its connection to Peter Parker's world is explored in a different way than in the official comics or movies.
Venom could be a hidden threat in the fanfiction. He might be lurking in the shadows, observing Spider - Man's every move during Homecoming. His presence could add an element of mystery and danger.