The Avengers: Age of Ultron ****Now with Spoilers in living Technicolor***

It's a really contentious relationship, too. Walk into a toy store and look for an X-Men action figure. You won't find any because they don't exist. Fox has to get Marvel's OK to produce figures, but Marvel doesn't want Fox to see any profits, so they refuse.

Marvel has also barred their comic writers from creating new characters in any X-Men related comic, because if they do Fox automatically gets the movie rights to that character. They're outright cancelled The Fantastic Four and mandated all artists not draw FF characters in promotional pieces because they don't want to give Fox's upcoming movie version any support.

The relationship with Sony is actually pretty good and there have been rumors as recently as last week of Spider-Man somehow crossing over into the MCU if a mutually beneficial deal can be struck. But Fox and Marvel despise each other.