In Greg Egan’s latest novel, as is not uncommon in first contact novels, the chapters alternate between the viewpoints of a human explorer and a member of the newly discovered species. In defiance of convention, Rakesh never finds Roi’s world. (There is room for a sequel, but I don’t expect one.) Roi lives in a tiny artificial world orbiting a black hole, and Rakesh finds a similar world orbiting a neutron star.
So why is Roi in the book? Because she is a leader in the blossoming of science in her world – going from pretechnological ignorance to general relativity in one lifetime, thanks to the peculiar environment – while the world contacted by Rakesh is stagnant.
And because Roi’s world figures in the central mystery of Rakesh’s world.