"Speaker for the Dead" by Orson Scott Card

This book was written before "Ender's Game" and the previous book was supposed to be just introduction to "Speaker for the Dead" while in reality ended up being more famous. The book is set 3000 years after the event in "Ender's Game". Humanity has settled the 100 worlds that the Buggers left behind and Ender's name is universally reviled as the Xenocider. Andrew Wiggin, traveling under his real name and as Speaker for the Dead, learns about Lusitania, the only planet where a new intelligent race was discovered, the Pecaninos, or the "piggies".

Since this planet has not been known during the Buggers, it is an enigma to the settlers, Brazilian Catholic community, who isolate themselves from the rest of the planet by the means of pain-inducing fence. Ender arrives on the planet after 22 years of space travel, as he has been called to speak the death of one of the Xenologists (Xanador in Portuguese) who was killed by the piggies. Ender brings the dormant Hive Queen as well, who chooses this planet as the future settlement site for the Buggers.

Eventually Ender brings all three communities together, even though provoking a harsh reaction from the other 100 worlds who see the piggies as a threat. It turns out piggies are half-animal/half-plant and they developed that way to adapt to the virus introduced on their planet which destroyed almost all species that couldn't switch to the plant/animal dichotomy. At the end of the book, the Hive Queen awakes and drinks water and eats while laying her first legs and enjoying being free.