Who does eliezer become friends with at the camp? What connection does he find between their lives?

You might be talking about the young French girl here. Eliezer makes friends with the girl after he is beaten by Idek. She tells him not to give up hope, and even gives him a bit of bread to eat. Eliezer believes that like him, the young girl is Jewish. He finds out years after the war that she was Jewish; she'd succeeded in passing herself off as an Aryan.