The world of the Simes and Gens is teetering on the brink. Zeth Farris reaches adulthood just when things start to fall apart. When he finally understands the audacity of the social engineering experiment that his parents have set in motion, Zeth must build bridges with potential allies to hold the center together. But war comes anyway, and Zeth and his alliance must prevail. The price of failure?--the destruction of his family, his culture, even his world! Sime Gen, Book Five.

In the far future a mutation develops and humankind is split into Simes and Gens. Simes "change over" at adolescence into vampire-like creatures that must suction off energy from Gens every month. Ordinarily, this causes the death of the Gen. But then "Channels" are discovered who could safely take energy from Gens and give that energy to Simes. Zeth is the son of the first such channel, Rimon, and a Gen mother, and born into a community struggling to find a new way for both kinds of humanity to live together without killing each other. Both Lichtenberg and Lorrah who write books in this series and wrote this book together are both good storytellers and create characters to care about. And since each book was written to be read independently, this one can stand alone. ( )

This series is a quick read and generally amusing. It brings up an interesting concept though -
in the future, the great hunger has come and gone. The overpopulation has crashed due to insufficient food for everyone. But SOMEHOW (there are differing theories as to just HOW) the human race has split in two.. Simes and Gens.
Gens generate a special substance called Selyn. They have a special transport system for this essence that is useless to them, and special receptors designed to accept a Sime's tentacles.
The Sime subsisted on this Selyn. They can consume regular food and it will carry them for awhile, but like a human without water - without Selyn they will die...and they will die insane, ravenously hungry, out to kill anything they get close to.
Together - Sime and Gen make a whole - the Generator to eat the food, converting it to Selyn, the Asimilator to milk the Gen of this precious nectar (they CAN live on only Selyn) - they double the carrying capacity of any land in which they live...except something went horribly wrong...
A Sime can only take a Gen's selyn with their death.

It makes a thought-provoking series about what might be - if we can't get our population under control! And also makes a good playground for differences we take for granted today. ( )

In the far future, the human race is divided into Sime and Gen, just as it is into male and female. Simes must take energy from Gens each month to live, but when they do so, the Gen dies. A rare type of Sime called a channel has been discovered, who can take energy from a Gen without harming them, and transfer it to an ordinary Sime. Can the shakey community founded on the ideal of unifying the human race survive in spite of opposition from both Sime and Gen communities? ( )