Lucy struggles to find her place in her adoptive group, most of whose members still treat her as an outsider. She learns what it means to be the lowest-ranking walker, and realizes that much of the group’s repressive character can be blamed on its greedy, power-hungry leaders, Bul and his evil mother, Sady.
She makes two female friends, but one of these flees the group soon after, having been gang-raped and beaten by Bul and his two allies. Lucy eventually mates with the leader, herself, despite finding him repulsive. She has no choice—he would hurt her or possibly even kill her if she refused.
Circumstances begin to look up for Lucy when she discovers she possesses a surprising talent with great potential for her kind’s way of life. Soon after, she meets the love of her life, a stranger named Gus, and she must put her new ability to work in a scheme to get him and his two friends admitted into the group.
Part One Parenthetica investigate Lucy’s species and their environment, social structure, intelligence, communication, and sexual habits. Other topics include food sharing, tool use, the beginnings of culture, male and female exile, the need to add meat to a vegetarian diet and early strategies for getting it, and a helpful guide to the comprehension of deep time.