Voiced by: Yūko Gotō
Riannon was the person whom released Arawn from his slumber. She is also Arthur’s sister. She takes a liking to Arawn instantly after she was saved by him and decided to marry him. She, like her brother, thinks simple as well, which sometimes causes Arawn to call them both 'foolish brother and sister'. She seems to show some possessiveness towards Arawn when Morgan tried to suck blood out of Arawn's injury. Riannon excels in recovery magic, life magic and wields a magic wooden rod.
Riannon's true name is Primula, a name that she uses to awaken her magical power. She and Arthur are direct descendants of Elf-King Pwyll. However, her parentage are mixed with humans so she is only partially Elf. She is also the descendant of Primula, the girl Myrddin rescued from the ice age made by the other 11 Angels.
Her name originated from the Celtic mythology, Rhiannon.