Many things about Valia's past are unknown. The only thing known about her is that she had two daughters, Yuuko and Valna, with an unknown person. At an unknown point, she sent Yuuko to the human world and left her with a human family. Many years later, Rogles, the ruler of the dark world, tried to take over Vanity and Reality with his army. As a result, Valia wanted to contact Yuuko and tell her the situation to convince her to become the new Valis warrior, but Rogles' attacks started before she could expect them so she gave Yuuko the Valis sword immediately and tried to explain the situation, much to Yuuko's disappointment. In the end Yuuko finally stopped Rogles' plans.
Some time after Rogles's defeat, the dream world enters in danger once again at hands of a new emperor, Megas, Rogles's younger brother who wanted revenge on his brother's regime and Vanity. During his attempt to do so, he killed Valia in the MSX2, PC-88/98 and Sharp X68000 versions, taking her as a hostage when she tried to help Yuuko after fighting Haizen. Megas tricks Yuuko into taking off her armor and leaving her sword to let Valia go free, but he lies and kills Valia in front of her. In the PC-Engine CD/TGCD version, she died from a terminal illness from which Yuuko didn't know about.
In the MSX2, PC-88/98 and Sharp X68000 versions, Valia's spirit appears in front of Yuuko after she defeats Megas to congratulate her, while in the PC-Engine CD version, she appears as a spirit in front of Megas to discuss with him about what moved him to take revenge against all of Vanity.
In Valis III an illusion of her appears when Yuuko, Valna and Cham try to approach the Nirvan temple, questioning their motivations. This was Valia's last chronological appearance. Much like Reiko, Valia seems to have finally rested in peace when Yuuko decided to not fight anymore for the peace of the three worlds.
In this version of Valis, Valia is a mysterious queen who kept the balance of the Dream world. She was kidnapped by Rogles by her own will. She reveals in the end that she was behind the events to find someone strong enough to possess as her body was disappearing. She tried to possess Yuuko but failed and finally seeing that the Valis energy font is loosing control because of her actions, she decides to become the controller by possessing the phantasm jewels and restores the balance to the Dream world.
Valia's personality seems to have different faces. In the first game, she is portrayed as a cold entity who only was worried about her world's sake and not about the sake of who fights for it (Yuuko). But in the second game, she seems to care a lot for Yuuko and always tells her to not give up, as here it's revealed that she is her mother also.
In the Famicom/NES version her personality remains in mystery. In a few parts she can be seen as a calm and mute woman.
Valia's few seen abilities were all related to magic. She can teleport herself and objects such as the Valis sword at will to any place (except when imprisoned by Megas). She can also talk by telepathy to other people.
As a spirit, she retains all her abilities and can still use her energy to talk and interact with live beings, much like Reiko does.
In the Famicom/NES version, she can use her soul's energy to harm others and also possess objects or even live beings.
In Valis SD she appears as a spirit telling Yuuko to defeat Megas after Yuuko figures that it was Megas that killed her.
She also appears in the new Valis manga by ZOL where she supports Yuuko and also sends Valna to help her.
- It's unknown what relation Valia's name has with the Valis sword.
- There is a young woman who strongly resembles Valia using the Valis sword during the intro cutscene of Valis III, although this woman was called Seanna by fans.
- Leigh from Valis III also has a slight resemblance to Valia in appearance.
- The Famicom version of Valis is the only game of the series where Yuuko fights Valia.
- In the MSX version of Valis I, there is a hidden room with many Valia statues.
- Valia is the opposite of Rogles in many ways, in a similar way of that of Yuuko and Reiko.
- They both are the rulers of two opposite worlds.
- They both use a long coat; while Rogles uses a black coat, Valia uses a white one.
- Their genders are opposite.
- They both use golden details.
- When Valia dies and her spirit appears, her hair, skin and coat's colour changes. In the MSX2,PC-88/98 and SX68 versions, her skin becomes white and her hair pink while in the PCE-CD/TGCD version, her hair colour becomes pale yellow, her skin white and her coat a golden-like yellow.
- The coat she uses when she appears in Valis III is coloured blue in the MD/Genesis version and purple in the PCE-CD/TGCD version.
- When going with Cham in the level where the heroines find Valia's illusion, if the player uses Cham, that could be the first time they meet in the main series.
- Strangely, Valia doesn't appear in Yuuko's flashback from Valis IV.