Stein 

Stein is Eliezer's cousin by marriage. He is desperate for news of what happened to his family. Eliezer lies to him, saying his wife and children are fine. This allows Stein to live as he has no desire to survive unless his family is well. Stein is one of the few people at the concentration camp that keeps his humanity and cares for others. He gives Eliezer his ration of food and gives Eliezer and his Shlomo advice on how to stay alive. The book does not state if he survives the Holocaust or not, but it is unlikely as he had not hardened himself emotionally he probably was unable to survive without his family.