Mein Freund Pax by Sara Pennypacker

When a young boy is forced to release his pet fox at the outbreak of war, both he and the fox set off on separate journeys that test their bond: the boy joins the fight and then struggles to find his way back, while the fox must learn to survive in the wild and forms an unlikely friendship with a grieving girl; told in alternating perspectives, the story explores loyalty, loss, the effects of conflict on humans and animals, and the slow work of forgiveness and healing.

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