Timer

Soulmate AU where everything is the same except that everyone can have a device installed that will tell them when they will meet their soulmate. (Concept borrowed from the movie Timer, which is great and you should see it!). Kara must deal with the fact that she may never be able to get a Timer installed due to her invulnerability, and she doesn't quite know whether that's good or bad. Things get more challenging for her when the person she's dating decides to get one installed. Meanwhile, Alex has to deal with the surprising result of her eventual soulmate and Lena Luthor wonders if she'll ever meet hers. Supercorp slowburn with a little Sanvers thrown in for good measure!