2015’s This Gulf of Time and Stars is the first book in Julie E. Czerneda’s Reunification series. It is set in her Clan Chronicles setting (first visited in her 1997 debut novel, A Thousand Words for Stranger).
Refugees without history, the surprisingly humanoid Clan live unseen amongst humans, who in turn live in the vast multi-species galactic confederation, the Trade Pact. The Clan’s psychic assassins eliminate any person unlucky enough to discover the Clan’s existence. Or rather, the Clan once lived unseen amongst humans. Now they live out in the open, outed by a biological trap of their own creation.
The Clan breeding program was so successful at creating females of unparalleled psychic power that no male can survive breeding with them. Hoping that the Trade Pact’s vast R&D resources can overcome the reproductive bottleneck, the Clan revealed themselves and joined the Trade Pact.
The Clan may have traded gradual extinction for swift extermination.