Calan by Christine Myers

Ajha Lann, a dawning psion grew up under the wing of an older girl. Together they scrounged for food and avoided capture by the gangers in the ruins of Farringay. Left on her own when Mikki is captured by gangers, the voices in her head seemed to get louder but one presence is stronger than the others. It gives her hope of something better for her future..

Calan Narcaza’s mother, the former Michelle Marlow was born in the ruins Farringay outside the Starport Compound. Little had changed since his father went to Earth to find Chelle and claim her as his mate. Calan knows the dangers, but he has felt Ajha Lann reaching out to him from several years. He knew that for her to reach him over such interstellar distance could only mean that she was his psion mate.

His brother Jamerin brings Calan to Earth in his starship, though he is skeptical about leaving his baby brother on his own. Then they find a cyborg in stasis at the industrial complex that Calan bought to give refuge to the people struggling to survive in the city ruins. They wake him.
Calan and cyborg Rax Ven become allies building the Refuge together and facing off with the Overlords and gangers in a final showdown.