The Reaping Room. Botanicaust

Humanity is on the brink of extinction in more ways than one. Michael is the smartest of the Fosselite children, trusted to help in his father's lab. The unconscious green people in there are not human; they are cannibals and must never be allowed to wake up. Although Michael doesn't like clearing the bodies when Father is done, he's determined to be a good boy. Then Tula arrives. She has green skin like the other cannibals, but she doesn't try to bite Michael.
In fact, she's the kindest person Michael's ever met. Even Father seems to like her and doesn't strap her down with the others. Michael is delighted to make a new friend. But when Father changes his mind, Michael realizes his obedience has been based on lies. With Tula about to be reaped, Michael is forced to choose between a lifetime of obedience to family and his own new moral compass. The end result will impact a lot more than just his life inside the Fosselite mountain.
It will change the future of humanity. This novella is part of the Botanicaust series--tales of humanity grappling for survival in a world decimated by genetic manipulation and coming to terms with what it really means to be human. Although it can stand alone, this novella is best read after reading book one in the series BOTANICAUST.