Well, perhaps in the fanfiction, Spider - Man bonds with Carnage to save an innocent person. Let's say Carnage has taken a hostage, and Spider - Man discovers that he can form a temporary bond to influence Carnage's actions. He then uses this bond not only to save the hostage but also to try and reform Carnage in some way. It could also be that the bond is a result of a magical spell gone wrong in the Marvel universe that links their fates together.
Maybe in the fanfiction, Spider - Man discovers that Female Carnage has a hidden side. She has some sort of soft spot for the innocent people in the city, which is contrary to what her violent nature implies. This discovery leads to an unexpected bond between them and they start to work together more closely.
One possible fanfiction could involve Spider - Man having to face off against Female Carnage in a battle that takes place in a crowded city. He might initially underestimate her power due to her being a female version of Carnage. But as the fight progresses, he realizes she's just as dangerous and has to use his wits and agility to try and subdue her without causing too much destruction to the city.
Well, it would be a very dark turn. Spider - Man is known for his heroism and moral code, while Carnage is a brutal and chaotic villain. If he became Carnage in fanfiction, he might start to use excessive violence and lose his sense of right and wrong. His relationships with his friends and family would be severely strained. For example, Mary Jane might be terrified of him, and his friendship with Harry Osborn would be in jeopardy. Also, the city he protects would be in chaos as he starts to go on rampages instead of saving people.
In this type of fanfiction, Spider - Man often becomes more complex. At first, he might be excited about the new powers the symbiote gives him. But as he realizes the downsides, like the potential loss of control, he starts to grow in self - awareness. He has to learn to balance his own moral code with the power - hungry nature of the symbiote.
For Carnage's character arc, you could make him initially just a mindless force of destruction. But as Spider - Man continuously thwarts his plans, he begins to develop a sort of grudging respect for the web - slinger. He might then start to target Spider - Man in more complex ways, not just brute - force attacks. This shows growth in his character from a simple villain to one with more depth. Also, you could have him face a situation where he has to choose between his own survival and the continuation of his chaos - creating ways, which could lead to an interesting internal conflict.
If Spider - Man becomes Carnage in fanfiction, the story might develop as he begins to target his former allies. He could go after the Avengers, thinking they are a threat. The other heroes would be reluctant to fight him at first, believing there's still some of Spider - Man in there. Meanwhile, a new character could emerge, someone who has a connection to the original symbiote that created Carnage and has the knowledge to potentially save Spider - Man. This would lead to a race against time to stop 'Carnage - Man' before he causes too much destruction.
In a more cooperative scenario, Spider Man's web - shooting could be used in combination with Female Carnage's shape - shifting. For example, she could transform into a large structure and Spider Man could use his webs to anchor it or create a web - based mechanism around it. Their powers could also clash in a way that creates interesting visual and story - based effects, like when Spider Man's web gets caught in Female Carnage's symbiotic mass and she uses it against him.
One interesting plotline could be the symbiote influencing Spider - Man's moral compass in ways he didn't expect. For example, it might make him more aggressive in fighting crime, but also more willing to cross ethical lines. Another could be the symbiote's memories from its home planet affecting Spider - Man's understanding of the universe. It might show him visions of otherworldly battles or technologies that he then tries to incorporate into his own crime - fighting methods. A third plotline could involve the symbiote bonding with other characters in the Spider - Man universe, like Mary Jane or Ned, and how that changes their relationships with Spider - Man and their own roles in the story.
One interesting plotline could be Spider - Man struggling to control the symbiote's more violent tendencies while still using its power for good. For example, he might accidentally harm an innocent while trying to fight a villain.