Andre Norton's "Star Born" pictures a human colony in another galaxy, driven away from Earth generations ago by a repressive government. Considered outlaws, the colonists are in permanent hiding.
They have developed friendship and cooperation with a local race of "mermen" who are equally at home on land or sea. But that race only took to the sea to escape a malevolent power that hunted them and killed them violently for sport - Those Others.
With a global decline in the population and reach of Those Others, contacts are few and the humans have no direct knowlege of them. So it is a major surprise when Dalgard, a human scout on his coming-of-age expedition, along with his "knife-brother" Sssuri of the mermen, run into a party of those others who are bent on reclaiming hideous weaponries left behind in one of their abandoned cities. . . and find that they are being aided by new arrivals from Earth.