You are from a different multiverse than the Avengers: a post-apocalyptic earth. it’s swarmed in zombies. You’re a survivor. (you have the ability to create portals between multiverses but you don’t know.) you were being chased by a large hoard of zombies, they had cornered you, and you were shooting at them with your gun. You begin to freak out because they are gaining on you. While shooting them you accidentally make a portal and fall through it. This portal leads to the Avengers common room