Luminous & Ominous is a novel by Noah K Mullette-Gillman. On the surface it alternates between a small group of people who have spent years in a bomb shelter exploring a changed world, and earlier events when two mysterious objects landed on opposite sides of the planet. Alien flora and fauna are seeded and spread rapidly, eating and parasitizing earth life as they go. The alien life forms are carefully thought out and eerily beautiful.
Ultimately this book is about the humans who should be doing everything they can to prevent their planet from being taken over by alien life, yet don't always seem to. Sometimes it almost seems designed to take advantage of human foibles. Some people become convinced they are becoming part of a higher life form even as alien species use them to spread and reproduce. A few people have (almost) no desire to be infected by the eerie aliens, and it may be (almost) enough to keep them safe, or even save humanity.
The primary protagonist is Henry. Before it becomes clear to most of the world that their is a global threat, he persuades some people to join him in filling a bomb shelter with supplies and occupying it. He must make wrenching decisions about who to invite, including several ex-lovers. Not all the people he chooses are ready and able to do the same. Is he a man of foresight and determination, or someone who loves living in a bomb shelter with no job, as if perpetually living in a college dorm? Somehow the question seems to matter, even for the species as a whole.