The little snake / A.L. Kennedy.

This is the story of Mary, a young girl born in a beautiful city full of rose gardens and fluttering kites. When she is still very small, Mary meets Lanmo, a shining golden snake, who becomes her very best friend. The snake visits Mary many times, he sees her city change, become sadder as bombs drop and war creeps in. He sees Mary and her family leave their home, he sees her grow up and he sees her fall in love. But Lanmo knows that the day will come when he can no longer visit Mary, when his destiny will break them apart, and he wonders whether having a friend can possibly be worth the pain of knowing you will lose them. --from Amazon.