You could add a time - traveler to Spider Man Volume 2 fanfiction. This character could come from the future and warn Spider Man about upcoming threats. It would also open up possibilities for exploring different timelines and how Spider Man's actions in the present can affect the future. Another option is to introduce a magic - using character. This would be interesting as Spider Man usually deals with science - based threats, and having to work with someone who uses magic would be a new and challenging experience for him.
One character that could be added is a new love interest for Peter Parker. Maybe a scientist who works at Oscorp and has her own set of skills and secrets. Another could be a young mutant who looks up to Spider Man and wants to be his sidekick. This would add a new dynamic to the story as Spider Man has to train and protect the young mutant.
A young tech - savvy girl who becomes Peter's sidekick of sorts. She could help him with his suit and gadgets, having hacked into some of Stark's old tech files. She's a bit of a loner at school but when she realizes Peter is Spider - Man, she offers her assistance.
Miles Morales could be a great addition. He has his own unique set of powers and a different perspective compared to Peter Parker. His inclusion could bring new energy and storylines to the team.
Sherlock Holmes could be an interesting addition. His deductive skills would complement the spy work of the U.N.C.L.E. agents. He could help them solve complex mysteries and outwit their enemies with his brilliant mind.
Penni Parker could be a great focus. In the movie, she doesn't get as much screen time as some of the others. Fanfiction could explore her backstory more, like how she became the SP//dr in her universe and what her daily life is like when she's not in the multiverse - saving action.
Adding a character like Amanda Waller would be interesting. She could be pulling the strings behind some of Peacemaker's missions, adding a layer of mystery and political intrigue. Or even bringing in a character like Green Arrow for a brief encounter to see how their different ideologies clash.
A young street - smart kid from the Vegas slums who befriends Spider - Man and helps him navigate the seedy parts of the city that he's not familiar with. This kid could have dreams of leaving the slums and Spider - Man becomes an inspiration for him.
One underrated character is Peni Parker. In fanfiction, you could explore her relationship with her SP//dr suit in more depth. Maybe she has to deal with some glitches in the suit that are affecting her performance as a Spider - Hero. Another character could be Spider - Ham. You could write a story where he has to use his unique animal - based abilities to solve a mystery in the multiverse that the other Spider - People can't.
Hermione Granger from the 'Harry Potter' series could be an interesting addition. She could use her magic knowledge to help the Ghostbusters understand the more esoteric aspects of the ghosts they're dealing with. Maybe she could even develop spells that work in tandem with the Ghostbusters' technology.
The Scarlet Witch could be a key character. Since she was central to the House of M event in the comics, her presence could add a lot of depth. Maybe she has some sort of connection to Spider - Man in this fanfiction, like she sees him as a key to either maintaining or breaking the false reality.
One underrated character is Robbie Robertson. He could be given a more central role in a fanfiction. Maybe he discovers some shady business going on in the city that is related to the villains Spider - Man faces. He could then team up with Spider - Man to expose the truth. Another underrated character is Betty Brant. She could be developed more as a strong - willed journalist who is trying to break big stories, and her relationship with Peter Parker could be explored in a different way.