A vision of Aslan
Aslan is a great, golden lion, king of Narnia in CS Lewis's series. Onni worships the Sun God, which this could be a reference to. Her father, Zodiac, also had the ability to turn into a Lion and was often called the Lionheart.
The story of a traveller
Onni was originally born in Isilme and traveled to Helovia after being ousted from her home.
The song of a Blue Jay
Species ref. Possibly a color ref to her eyes as well.
The laughter of a child
Personality reference. Onni is very lighthearted and kind.