Patricia A. McKillip, The Moon and the Face (Argo, 1985; Puffin, 2005)
In The Moon and the Face, Patricia McKillip revisits Kyreol and Terje from her lovely Young Adult novel Moon-Flash. Kyreol and Terje, having followed the river to the Dome in book one of this duology, now push beyond the new boundaries of their expanded world: Terje back into the culture they left behind, though as a ghostly observer; and Kyreol outward, into the stars. When Terje discovers the Healer (Kyreol's father) is dying and Kyreol barely survives a crash landing on a distant desert moon, both of them must find inner resources to meet challenges they never anticipated.
While not quite as spontaneously joyous and lovely as the first book, The Moon and the Face is still a great little novel. As with Moon-Flash, I was almost overcome with gratitude for the lack of antagonistic forces and the complete absence of evil intentions. The characters are presented with challenges, yes, and death and fear, physical hardships and emotional turmoil, even grief and sadness. But never ill-intent nor maliciousness of any sort. It's something I only notice by its lack, and I like it, particularly in novels intended for younger people.
I also liked that The Moon and the Face, while retaining the mysticism and almost dream-like fantasy setting of the Riverworld, also brought into play a more science-fiction feel with Kyreol's sojourn to space. Her story, shipwrecked as she is on an alien moon, is really one of first contact with an alien species. Terje, a more major player in this second novel, is reunited with the world he left behind, in moving and profound ways. As always, the relationship between the two young characters, though they spend most of this segment of the story separated by vast distances, is touchingly romantic in the sweetest, most sincere and egalitarian way.
Another great book to give the younger readers in your life.