The friendly river fairy resides in moving water and watches over the stream or river in which she lives. She morphs between a humanoid form and a water form, with the ability to alter the size of both form. When angry, the fairy rushes down her banks in the form of raging waters, causing flash floods. The otherwise calm fairy becomes particularly angry when people abuse her river by littering; according to legend, angry river fairies have wiped out entire historical cities when they polluted bodies of water.

However, the fairy usually has a very giving and loving personality. For example, if she sees a struggling animal or person in her river, she will wash them ashore. Once, a river fairy swept fish onto the banks to feed a lost and hungry person. Conversely, she has swept beached fish back into the river. She also sculpts fairy stones, the stones through which moving water has eroded a hole, that allow humans to see invisible or otherwise magically hidden fairies. She places the stones where those she deems worthy can find them. She enjoys leaving other gifts as well, like precious gems, for good-hearted people to discover.

The fairy sometimes entertains herself by arranging river rocks into elaborate and ornate patterns. According to rumors, if a person recognizes the pattern and whispers its name aloud, the fairy will bestow a very desirable and sacred gift upon him or her.