Alright, I'm also gonna reveal what could have been.

The story I originally had in mind was not in the same Brothersverse setting. Instead, it was set in another setting. Something a little more similar to The Death of Nicholas Santos in which it's a crossover.

The basic gist was that, in a Last Temptation-style illusion, the main character winds up in an alternate reality where the love of his life was still alive. However, he is immediately made aware of the fact that he's in an illusion devised by the antagonist and that he's supposed to stop her and save the multiverse. However, it's hard to do so when you're constantly seeing the person you missed so much. 

In the end, the main character leaves behind the burden of saving the multiverse in favor of living in the delusional world, much to his mentor's chagrin.