If I had written Spider-Man 3, it would have ended with a few unresolved cliffhangers. Spider-Man and Mary Jane are worried because Harry Osborn is on the loose as the new Green Goblin. They’re unaware that Eddie Brock, a suicidal Daily Bugle photographer who hates Peter Parker, has become the new Venom. And it would’ve been filmed back to back with Spider-Man 4.
These were my musings as college student who enjoyed the hell out of Spider-Man 2, but figured if they were going to do the alien costume saga and the Harry Osborn Green Goblin saga, they needed it to be at least two movies.
Before Spider-Man could deal with the other bad guys, he’d investigate the disappearance of Professor Curt Connors. This would lead to an encounter the Lizard. He might be interrupted by Martha Connors, who would reveal that her husband has been transformed into the monster.
Spider-Man tries to develop a cure for the Lizard, and hunt him down. The battle between Spider-Man & The Lizard is broken up by an attack by the Harry Osborn Green Goblin. Spider-Man allows the Lizard to escape, rather than risk the Green Goblin killing him.
After Spider-Man cleared his name, Flash Thompson has become a big fan of Spider-Man.
The Green Goblin abducts Mary Jane, and brings her to the Brooklyn Bridge. She believes so he could finish the job that his father was unable to finish. He reveals that it’s to prove that he would never hurt her, no matter what goes on between him & Spider-Man, similar to the opening of Spectacular Spider-Man #200.
Venom ambushes Spider-Man, and leaves him for dead under hundreds of tons of wreckage, before deciding to replace Spider-Man as a superhero.
Mary Jane has to cover for the missing Peter.
Venom brutally beats on the Black Cat, who is trying to be a hero like Spider-Man.
Mary Jane confronts Harry, who claims to know nothing of Peter’s disappearance.
While searching for Peter, Mary Jane is accosted by thugs. She is rescued by someone she thinks is Spider-Man, but it’s really Venom, echoing her encounter with Kraven in Kraven’s Last Hunt. The experience scares her. When she gets home, Eddie Brock is there.
Eddie Brock convinces Mary Jane that he, and Peter were good friends, and misleads her as to why Peter’s gone missing. He claims that his reason for getting fired from the Bugle was that he knows who the Green Goblin was. He uses the alien costume’s memories, and brief meeting with Aunt May to enhance the illusion. He decides to claim that Jon Jameson is actually Venom.
The Lizard slowly heals, plotting a violent revenge against the mammals, with his ability to control all of the reptiles.
A very angry and injured Spider-Man crawls out of the wreckage after being buried for days.
He confronts Venom, telling MJ to run. Venom evades him, leaving Spider-Man in a position where he has an enemy who knows his secret identity and has his powers.
Needing help, Spider-Man goes after the Harry Osborn Green Goblin, since he still needs to fight the Lizard and to cure Venom.
Green Goblin 2 confronts Spider-Man. Spider-Man asks for help against his enemies. At this point, they both have power and responsibility.
Harry decides to help Spider-Man against Venom. Harry and Venom both die.
Mary Jane is heartbroken. Spider-Man is devastated, but he pushes his feelings aside to find the Lizard, and cure him. That inspires him to keep at it.