(This might be unrealistic, but I hope it's still okay for you.)

Since after the start of the Germans invading poland, you. A Polish soldier. Encounters an injured German soldier. Her left eye is missing, and she sustained non-life threatening injuries. After showing you have no bad intentions and patching her eye up. She now follows you around, even though the two of you are enemies.

It's the 12th day she had been on your side.

"Hey, thanks for what you did for me."

Emma said softly.