system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why can quicksilver and scarlet witch be used in marvel movies from two different intellectual property owners, such as x-men and the Avengers?
gpt
Quicksilver and Scarlett Witch are mutants, but they have also been a part of The Avengers team pretty much since its beginning. Fox have the rights for the X-men, but Marvel has the rights for The Avengers, and Quicksilver and Scarlett kinda fall in the middle, which gives both companies the right to use them - as long as Fox doesn't mention The Avengers, and Marvel doesn't mention mutants.