Two short stories, spaced five decades apart, featuring aspects of a society at the given time periods.
(Optional note, summarized in the story): The two parts to this story are written in an arbitrary order, not necessarily chronologically, meaning either one can be considered the "first" on the timeline. The dates before each can be read in different ways since only the last two digits of the year are given(i.e. the date of the first, 08.18.43, can be read as October 18th, 2043 or 2143, which in turn can be seen as before or after August 23rd, 2093, an interpretation of the second story's date), and the only definite timing is that the two events take place 50 years apart. The two parts, Diem (day) and Noctem (night), can precede or succeed one another depending on perspective, in the same way night and day would. A few hints for causality are placed in both, some reflecting opposite interpretations.
A girl from Earth-616 (let's call her Elara) starts having vivid dreams of a mysterious guy playing basketball in a world that looks almost identical to hers. She doesn't know that her seemingly small decisions-turning left instead of right, spilling coffee, choosing to skip a class-are changing events in his world.
The guy (Riven) lives in Earth-717, a parallel version of her world, but slightly different in history, technology, and fate. One day, after a strange phenomenon, he starts noticing small glitches-objects appearing out of nowhere, memories that don't belong to him, and a haunting feeling that someone is watching his life from afar.
Through an accidental event (maybe a butterfly lands on Elara's hand, causing a chain reaction), the two universes slightly overlap, allowing them to see and hear each other in reflections or shadows.