Gauche’s return appears to have been an act by Noir, and he returns to Reverse after persuading the double-agents Valentine and Garrard that he’s Noir by attacking Lag (whom the agents kidnapped thinking it was Sylvette). After Noir mistakenly believes Lag is dead, Jiggy Pepper shows up and returns Lag to the Hive. Meanwhile, Zazie catches up to Cabernet but is stopped by another Maurauder while Noir and the agents head to a an abandoned research facility and find two survivors.
So we learn that the AmberGround artificial sun is allegedly powered by people’s hearts, including Lag’s mother’s and Gauche’s. We still don’t know what caused the Day of Flicker, though it is alleged by Reverse that the government started their experiments trying to create artificial spirit afterward. However, all of their experiments fail, and all the subjects they experimented on – people without a spirit – are disposed of, bar a few who happen to escape, most of whom joined Reverse.
Of course, this brings up the problem that if Bees fight the Gaichu because they eat people’s spirits, how can they stand by and let the government do the same thing to power the artificial sun? Of course, this fact is hidden from them, and I think both Lag and Zazie would doubt the claim that this is the truth, but I have a feeling eventually they’re going to be convinced this is the truth and end up joining Reverse to stop the government’s activities.