Using a slightly different jumping off point than below, What if Bob Kane and Jack Kirby Created Batman for Timely Comics?
When Bob Kane thought up the idea for Bat-Man, he shopped around the idea until Timely Comics took up his idea. With Jack Kirby on staff, Kane developed a more "patriotic" hero to keep in step with Timely's demands for another "Superman" or "Captain America", which were competitors to Timely Comics.
As Kirby later recalled:
“ ...had an idea for a character called 'Batman', and he'd like me to see the drawings. I went over to Kane's, and he had drawn a character who looked very much like Superman with kind of ... reddish tights, I believe, with boots ... no gloves, no gauntlets ... with a small domino mask, swinging on a rope. He had two stiff wings that were sticking out, looking like bat wings. And under it was a big sign ... BATMAN.
And I thought to myself, 'You've got to be kidding.'"
Kirby helped develop more of an active pose for this Batman. He made him darker, red with black tights, and red gloves with two reddish wings that jutted out from either side. Kirby is credited with the name too, "Steven Rogers", and was so influential in the style, he was given co-creator credit for Bat-Man.
Kirby and Kane's collaboration as a rocky one, but they were able to create an interesting character out of Steven Rogers. Originally a child of wealth in Eastern Europe, Steven Rogers' family was put to death by Nazis. Borrowing alot from the Scarlet Pimpernel and Pulp Detective stories, Steven Rogers used his secret wealth to escape to America, where he built himself up to become the Escape Artist/Hero/Spymaster known as The Bat-Man.
Timely's Dark Big Three (Human Torch, The Bat-Man, and Sub Mariner) went up against National Publication's lighter Big Three (Superman, Captain America, and Wonder Woman) in many head-to-head fights, eventually leading to National Publications leading the pack after WW2, while Timely folded in the 1960s.
When Timely evolved into Marvel Comics in the 1960s, Stan Lee revitalized Bat-Man when he reintroduced him in the Avengers. Frozen in a cave in the Antarctic, The Bat-Man was rejuvenated by Avengers Super-Science and brought back to life. The Bat-Man escaped Death and became a staple of Marvel Comics ever since as the remarkable performer Bruce Wayne by day, and Bat-Man, Agent of SHEILD, by night.
What kind of stories arose from Batman being the staple of the Marvel Universe instead of Captain America? Is there a Frank Miller Days of Future's Past with Batman hunting down mutants? Is Nightwing around, or did he go to law school and become Daredevil? Did Jason Todd become Nighthawk? How would Batman have faired against comparable Marvel foes considering he has no serum?
Let me know what you think.