One day you are presented with 2 doors: one leads to a real-life Marvel universe, the other to a real-life DC universe (the “primary” universe of each, so “Earth-616” in Marvel, and “Prime Earth” in DC for those of you who are going to get all technical).
You’ll not gain powers and become a superhero or villain, you’ll still just be you, but in the fictional (but now very much real) universe you chose. There is no returning to “normal” real life Earth.
Which door do you walk through?