No. Fanfiction involving sexual content based on family - friendly works like 'The Incredibles' is not appropriate. 'The Incredibles' is a movie aimed at a wide audience including children, and creating sexual fanfiction goes against the spirit of the original work and is also unethical in terms of violating the family - friendly nature of the source material.
No. Fanfiction involving sexual content related to family - friendly franchises like 'The Incredibles' is not appropriate. Such content goes against the family - oriented nature of the original work and can be considered unethical and inappropriate for general audiences.
One alternative could be creating family - friendly fanfic that focuses on the adventures of the Incredibles family. For example, you could write about a new mission they go on to save the city from a new supervillain.
It can damage the reputation of the original 'The Incredibles' franchise. It also makes the fandom less inclusive as many fans, especially those with family values, would be turned off by such inappropriate content.
The Avengers would likely have a range of reactions. Captain America would respect the Incredibles' sense of justice. And the Hulk might just be confused at first but then find it cool.
If the Avengers watched The Incredibles, it could be a very interesting scenario. The Hulk might get a bit jealous seeing Mr. Incredible's strength at first. Black Widow would notice how Mrs. Incredible manages to be a great mother and a superhero at the same time. Hawkeye would be interested in the archery skills of any character in the movie who might use a bow. And they all could learn something about teamwork from the family's dynamic in the movie.