Margaret and The Pope Go to Assisi by Jon M. Sweeney (The Pope's Cat, Book 4)

In this fourth installment of "The Pope's Cat" series, Margaret and the Pope travel for the first time together away from the Vatican and out of Rome. They go by train to the Umbrian hill town of Assisi, a place of pilgrimage for Christians all over the world who want to remember the life of St. Francis of Assisi. Together they visit the great Basilica named for St. Francis, greet Franciscan friars at the monastery, attend a World Day of Prayer for Peace, meet religious leaders (each, it seems, with a very different hat!) from around the world, and see evidence of the spirit of St. Francis all over town.

Most of all, the Pope shows his love and care for his vulnerable creature friend, as at the beginning of the book when someone from the Curia has frightened Margaret and she's hiding in a closet in the Pope's apartment. “Don’t worry, il mio amore.” (Il mio amore means “My love.”) “People can be so fussy, can’t they?” the Pope says, picking her up in his arms.