I am going speak her of her role in Valkyrie Profile : Lenneth, where she is the main character. What I am going to write is really very summarized, I'll write more in depths in a next update.
Lenneth is summoned by Odin, the Lord of the Gods, due to the fact that Ragnarok will arrive soon : the end of the world. For winning the war against their ennemy, Odin needs warrior coming from the human world, Midgard.
Lenneth's role is to go on Midgard find the soul of brave human on the point to die. Those if they accept will become her Einherjar. Lenneth has for Mission to train them and to send them to Valaha for fighting in the sacred war, all
of this supervised by Freya.
But it cannot be so simple. Lenneth, while she is going to do her mission is going to remember a past, her past while she was in sleep mode before Odin summons her : in truth, she was previously reborn as an human girl nammed Platina.
For avoiding that those memory makes her act from a way displeasing to them, Freya sealed her memory away. She died as human at 16 year and was a girl at miserablme life. She died, in letting herself die, in the arm of a boy who loved her.
Of course, when the fate is in the game we must wait special things, and now the boy has grown and Lenneth meet him! She is even going to take him as Einherjar at his death.
How does it end? There is 3 different end, but only one considered as Canon. The End C shows Freya killing Lenneth because you played in doing nothing of the job of Valkyrie. This is the bad ending, for seing we must have not luck and having playing from a way to displease Freya.
The B End shows Lenneth killing Surt, the ennemy of Odin, and winning the war. Freya said bravo to Lenneth. Abd it is the end. It is the middle ending.
The End A, the one considered as canon, is the good end, where Loki betrays Odin and destroys everything, but
Lenneth becomes Goddess of creation and recreates the world, destroys Loki, recovers her memory and spend her days with Lucian.
How could this wonderfull Valkyrie becomes creator? It is time to mention Lezard Valeth. Speaking of Lenneth without speaking of him would be hard. He was a brilliant mage before turning to dark Art. He loves Lennet above all, all what he does is turned to conquer her. He created for her some alernate body known as homunculus, because he wants her as human. Even if Lenneth didn't want use them, she will have no choice when Hrist will take her body.
Hrist, her elder sister, was ordered by Odin to take the place of Lenneth when she recovered her memory. Arngrim and Mystina, two of Lenneth's Einherjar could take her soul dammaged because Lenneth protected them from Hrist. Lezard helps them in putting her soul in an homunculus, but needs her true body
to save her soul. They go fight Hrist. The fact to make merge her old body and her homunculus will allow to Lenneth of see her power grows and reach the state where she is, for protecting all living being.
Brahms, Lord of Undead helps them. Hrist was attacking him, but her power were not fully awakened. Lezard, Brahms, Arngrim and Mystina together defeats her, and regive life to Lenneth.
At the end of the A Ending, Lezard is the only man having survived Ragnarok in using the Philosophal Stone. He promises to acquire Ultimate Power and resays his love for Lenneth...
Our belobed goddess can be seen like evolving in the game. Not only because her past is unsealed, but she becomes less cold. At beggining she hides her emotion, but quickly we see that she has a great heart, and during the game, we see it more and more.
She doesn't consider her Einherjar as mere tool, but she likes them, she is even ready to die for saving them when Hrist try to kill them. At the end, she becomes Goddess of Creation, and save the universe.