In the novel, The Devil's Arithmetic by Jane Yolen, Chaya is the girl Hannah becomes when she is transported in time back into World War II and the Holocaust. In modern time, Hannah does not understand why her Aunt Eva and her other relatives keep remembering the past. When Hannah becomes part of the past, she keeps her memories for a while and is now called Chaya. She is sent to a concentration camp, and the man who tatoos numbers on Chaya tells her that life cannot be lived without memories. In the camp, a girl named Rivka helps her live and survive in the camp. Hannah now realizes that her Aunt Eva is Rivka and that Chaya, whom she has become, is her aunt's friend. When Rivka is chosen for the gas chambers, Chaya pushes her aside to take her place. Therefore, Chaya is Aunt Eva's friend who died in her place during the war and for whom Hannah is named. When Hannah returns to the present, she now understands the meaning of her name, who Chaya was, and why memory is so important. I also think that Chaya represents the many brave Jewish people who tried to help each other survive, and live to remember to keep alive the people and story of the Shoah.
Chaya is Hannah in the book and then later when she is in WW2 in the holocaust she turns into Chaya who is Aunt Eva's dead friend ,and her best friend.