In Lois Lowry's novel Number the Stars, Annemarie Johansen and Ellen Rosen are best friends. They share many characteristics and differences as well. Both girls live in Denmark during World War II. They attend the same school and are both good students, though Annemarie claims that Ellen is a better student than she is. They are not biological sisters, but they pretend to be so that Ellen won't be captured by the Nazis. Ellen and her family are Jewish. Annemarie's family are Lutherans. The Johansens agree to hide Ellen when the Nazis announce they are taking all Danish Jews for relocation. Annemarie had a sister who died, so Ellen takes on her persona, telling Nazi soldiers her name is Lise. Ellen is an only child and her parents have left Denmark to escape the Nazis.
Ellen wears a necklace with the Star of David, which identifies her as a Jew. Annemarie doesn't wear anything around her neck.
Physically, the girls are quite different. Ellen has dark hair worn in pigtails. Annemarie's hair is a silvery blond and she wears it down. Annemarie is tall and lanky, whereas Ellen is shorter and stockier.