Singularity
Thoughts
Warn
Spoiler warning!
I don’t remember much in the way of specifics other than the main character lives in a bunker that is connected to a Black Hole for a period time in order to age himself up relative to his brother, I think. There’s some kind of spooky entity in the black hole/portal that continually gets closer over time until, eventually, it gets to the bunker’s side of the portal and destroys it.