can somebody explain to me why all the Marvel characters are spread across different companies?
They licensed their characters to various film studios in the 90's & early 00's because they were independent at the time.
In the mid-2000's After the success of the X-Men & Spider-Man movies, Marvel Studios realized they could self-produce their own films & do them better. The 1st being "Iron Man" (distributed by Paramount Pictures) in '08, than "The Incredible Hulk" (distributed by Universal Pictures) later in '08.
Disney bought Marvel Entertainment in late '09. But because of Marvel Studios's existing distribution deal with Paramount Pictures, Paramount still distributed "Iron Man 2", "Thor", & "Captain America: The First Avenger".
On October 18, 2011, Disney bought out the distribution rights for "The Avengers" and "Iron Man 3" from Paramount Pictures. However, as part of the deal, Paramount's logo will still be used in the promotion marketing and trailers for both films.
You can read more info about it here:
Marvel Studios - Wikipedia, the free encyclopedia
That's crazy...How the fukk DC surviving?
DC Comics has been owned by Warner Bros. Entertainment since the 1970's. So they have a big corporation backing them.