Clownthebaskingshark
Preface: This is loosely based on X-Men evolution, in that most of them are teens. However, Remy and Rogue are dating, and both teens and Kurt is an adult. The X-Men are still a secret from the world as well. As for the MCU aspect, this AU would take place shortly after Homecoming, except Peter accepted Tony's offer to be an Avenger. Also, in this AU, the spider bite caused Peter's x-gene to activate.
Peter Parker has a problem; his powers are advancing. He no longer needs webshooters; his body produces his own. He can see in the dark, and he doesn't know how to turn it off. He doesn't want to tell Tony. He'll only worry, and he just became an Avenger. He doesn't want to risk it.
Then, one day, a mysterious letter comes for him in the mail: Join the Xaiver Institute. Ever since then, he's been spending the weekends at the X-Mansion and telling Aunt May she was with the Avengers, while he's been telling the Avengers he spends the weekend with Aunt May.
What happens when his lie crashes down around him?