Gluck is a 12-year-old boy living in the highly fertile Treasure Valley of Stiria. Unlike his cruel elder siblings, he possesses a kind and gentle disposition, showing sympathy for the hungry and vulnerable. He is forced to perform the household's menial labor and frequently endures physical abuse and starvation rations from his brothers.

Schwartz is an elder brother to Gluck and co-owner of the Treasure Valley estate. Known locally as one of the Black Brothers, he is a greedy and ruthless farmer who hoards corn to sell at inflated prices during droughts. He openly mocks the poor, kills any wildlife that does not turn a profit, and rules his household through intimidation.

Hans is the other half of the notorious Black Brothers who control the wealth of Treasure Valley. He mirrors Schwartz in his avarice, regularly cheating servants out of their wages and refusing to extend basic human decency to his neighbors. He views all living creatures, including his youngest brother, entirely through the lens of potential profit and utility.

The King of the Golden River is a magical being who begins the story trapped under an enchantment, appearing only as a fierce face on Gluck's golden drinking mug. Once freed, he reveals himself as a small dwarf with flowing golden hair and sharp eyes. He carries a stern, unpredictable disposition and functions as a supernatural authority figure who dictates the rules for turning the local river into gold.

Southwest Wind, Esquire, is an eccentric, diminutive gentleman who wears a towering conical cap, corkscrew mustaches, and an enormous black cloak. Though he appears as a soaked and shivering traveler, he is the personification of a powerful natural force. His arrival at the brothers' home serves as a severe test of their basic humanity and hospitality.