Sonna has pale pink/purple skin, blue eyes with pink eye shadows, red lips and red body-tail with music sheet-like patterns. She wears a red spiral shell-shaped hat decorated by two flute-like corals, one is pink and one is purple. A transparent blue veil attached to the hat. She has a purple harp-shaped symbol on her forehead.
Sonna has been described by Musa as having a bad temper. Besides that, she is determined, when she fought the Devourer. She seems to be tough, but if she is threatened by bigger creatures, she would become afraid.
In the Winx Card Game App, she is described to be a capricious, sensitive and nervous Selkie.
When Tritannus is about to travel to Melody by opening its gate, Sonna closed it again. She was cornered by his mutants, and Tritannus stole her powers. Through bonding with Musa, she regained her powers. Later in the series, she converged with the other gate keepers to heal the Source of Sirenix in the cave of Lake Roccaluce and entered she Infinite Ocean with the Winx and Omnia.
She also appears with the other Gate Keepers whenever the Winx enters the Infinite Ocean.
Winx Club: The Mystery of the Abyss
Sonna makes an appearance of where Omnia was and trying to get away but Tritannus got there in time before she could escape. Herself and the other Selkies were trapped in a stormy barrier, preventing them to not leave it and were cover by something not letting them to speak. Then herself and the Selkies followed to the Winx where the hidden pearl was and stays outside to warn Omnia if Tritannus escaped with the pearl. She was last saw when they danced around in a line then Omnia.
- Issue 104: The Mirror of the Sea
- Issue 105: The Jaws of the Abyss
- Issue 110: The Magical Valley of Linphea
Sonna, with the aid of the harp symbol on her forehead, she can close and open the gate to Melody, enter the Infinite Ocean and shoot purple energy bolts. She can also converge her powers along with other selkies as seen in multiple episodes in Season 5.
As seen in "The Emperor's Throne," she and the other selkies can converge their powers to give the Winx a power boost.
- Unlike the other Selkies, Sonna bonded with Musa while she was a monster which turned Musa back into her old self.
- Sonna has the same voice actress with Stella in the Original/Italian dub.