Shadowreaper98
New York is home to many heroes, but none are more prominent than the Avengers, and the Fantastic Four, both teams have saved the earth, and even the universe on several occasions leading to these two teams having a rivalry, what happens when the two teams decide to use their youngest members to figure out the best, during an invasion of demons from another dimension the Fantastic Four bring out their two newest members Spider-Man and Spider-Woman also known collectively as the Spider-Twins, and the Avengers show case their youngest member Shadow Rider.
Not gonna bash any characters at worst the Avengers and FF have a friendly rivalry they never put it above protecting the innocent, I just got the idea one day of Spider-Man and his oc twin sister that I always use Petra Parker being adopted into the FF while Cain is basically the unofficial adopted son of the Avengers.