Mission: It's Complicated

You are a mild-mannered PhD candidate studying superheroes. More specifically, how they form bonds in high-risk situations. That is, until another you from an alternate Earth contacts you and warns you against the impending destruction of the Earth at the hands of Gidheron, Eater of Possibilities. To stop Gidheron, you need to find the Possibility Stone and you need two heroes to wield it. And they need to be in love.