Ariel is the youngest daughter of King Triton and Queen Athena, rulers of Atlantica, and has six older sisters. She is often seen in the company of Flounder, her best friend, and Sebastian, her father's advisor who is often assigned to watch over her. In the television series and first film, Ariel has a fascination with the human world and often goes off to find human artifacts that she displays in a secret grotto. Ariel is often rebellious, wandering off on her own to explore her surroundings, and frequently disobeys the orders of her father or Sebastian, causing conflict between the characters. In The Little Mermaid she is depicted as being willing to do anything to be with Prince Eric even giving up her voice to become human. Clements described her as a typical teenager, prone to errors of judgment. She also is incredibly curious, and her curiosity often leads her into dangerous situations.

Ariel is kind to others no matter what their circumstances, as depicted in the television series. In an early episode, Ariel helps an orphaned merboy who had fallen in with a bad crowd. In another episode, Ariel befriends a supposed bad-luck creature and protects it from Ursula and other merfolk who wish it harm. Ariel appears as an adult in Return to the Sea, and gives birth to a daughter named Melody. Ariel is protective of her daughter, as Triton was of Ariel in the first film. After Morgana threatens Melody, Ariel refuses to let Melody in the ocean. Ariel's Beginning depicts her personality as it was in the original film, after Jodi Benson had advocated returning the character to her roots. Ariel regains her rebellious personality, and after her father decrees music to be banned in Atlantica she runs away with Sebastian and his band.