Johannes encounters the figure called "Compagno di viaggio" while traveling alone, grieving his father's death. The companion voluntarily joins his journey without disclosing his motives or origins. Throughout their travels, he displays supernatural resourcefulness. He employs a magical ointment to heal an elderly woman, receiving three rods as payment. Later, he uses the same ointment to repair a broken marionette during a puppet show, earning a sabre. He also collects the wings from a dead swan they find. These gathered objects prove crucial later.

When Johannes resolves to confront the cursed princess who executes suitors failing to guess her thoughts, the companion secretly aids him. Using the swan's wings, he follows the princess as she flies to a mountain troll and overhears the solutions to her riddles, relaying them to Johannes. On the third night, after learning the princess must think of the troll's head, the companion beheads the troll with the sabre and gives the concealed head to Johannes. Johannes presents it to the princess, breaking her curse and winning her hand.

After the wedding, the companion instructs Johannes to fully free the princess by immersing her three times in water mixed with the swan's feathers. Once her liberation is complete, he reveals his true identity: the spirit of the deceased man Johannes protected from grave robbers by paying his debts. His assistance was repayment for that kindness. With his debt settled, he departs permanently. The companion functions as both a supernatural helper and a moral symbol, embodying gratitude and the fulfillment of unspoken obligations. His actions resolve the central conflict and enable Johannes's transition from wanderer to royalty.