The Vow to be Brother and Sister.Ronja thinks about what will happen to her if it starts snowing again while she is stuck. Meanwhile the Rumphobs have fashioned her foot into a swing for their baby's cradle to rock him to sleep as she struggles, wiggling her foot. A harpy spots Ronja and starts taunting and threatening her before attempting to free her in order to make Ronja her slave. The harpy tries to fly away with her in vain but promises to return the following day with her sisters to help her. Ronja's life flashes before her and she gives herself up for being lost to die in the cold. Ronja wakes up to find Birk calling her name and mildly chiding her for losing her ski and getting stuck before she breaks down crying in relief to see him. Ronja clings to Birk and begs him not to leave her and he jokes only if it's a rope's length away. Birk goes to work to free Ronja's foot and succeeds after some time. Birk follows after Ronja to make sure she gets home safely and Ronja asks him to be her brother to which he complies, calling her 'Ronja, my sister.' The next morning the Mattis Robbers find themselves snowed in and Ronja wakes up with a fever, collapsing on the floor.