Rat and Mole are close friends. Water Rat is an extrovert, and Mole is an introvert. We can tell they are friends because they hit it off from the start of the book, when Mole comes out of his underground hole to see the wider world for the first time. He meets Rat and goes off with him in his boat, which he loves from first sight. The two complement each other almost perfectly, as the friendly Rat enjoys showing Mole around and the shy Mole needs someone to help him adjust to the world above ground.

Their friendship is cemented when Rat takes Mole home for dinner, entertains him with stories, and later shows him how to swim and row. Rat and Mole are almost always together.

Rat takes Mole to meet the wealthy Toad, and because Mole is so filled with longing, the three take a trip to the country away from the river. When Mole, however, realizes how badly Rat wants to go back to the river, he

reached out from under his blanket, felt for the Rat's paw in the darkness, and gave it a squeeze. "I'll do whatever you like, Ratty," he whispered. "Shall we run away to-morrow morning, quite early—very early—and go back to our dear old hole on the river?"

Because of his feeling of friendship for Rat, Mole is willing to give up his trip.

Later, when Mole gets lost in the Wild Wood, it is Rat who searches him out and finds him. It is also Rat and Mole together who learn the true meaning of the song of the wind in the willows when they have an experience of the presence of the "kindly demi-god," the spiritual being who brings them to their knees in awe.