Question: What about Ryan and Ryan?

SPOILER

It opens up with Ryan from another timeline wanting to Kill Ryan in our timeline because the longer our Ryan lives...the worse, apparently. The end.

Did I miss something?

To me, it seemed the other Ryan is never explained. And why he has to kill the real Ryan in this timeline quickly... was never explored.

Is this Ryan vs. Ryan thing still going on?

My best guess is just that some experiments in another parallel world, somehow involving a completely different set of issues was the beginning of this story. And then she shoots into another timeline starting on her own adventure. And this is what the movie decided to follow (instead of poor Ryan)... an odd way of telling a story. But, from a certain point of view, quite befitting for a tale of many-worlds.

Of course, it seems her solving the issue with the Sissy, solved the original Ryan issue too. So are we to take it, that those equations they all worked hard on solved Sissy issues in all the timelines simultaneously?