Valkyrie of the Nordic Ascendant

Valkyrie of the Nordic Ascendant, usually simplified to Valkyrie, is a duel monster, and one of the original members of Celtic Guardian's rebel army. She is an all-around character.

A former agent of The Sanctuary in the Sky, Valkyrie betrayed the sanctuary due to her belief that life on Earth was worth protecting.

Backstory
Before Answers, Valkyrie lived in The Sanctuary in the Sky, and worked as an agent that would go to Earth as a scout, for the sole purpose of seeing to it that the planet would be easy to destroy.

While scouting Earth, Valkyrie had her first contact with humans. She noticed, startlingly, that they weren't too different to the monsters she surrounded herself with, even if they had soft bodies and no powers whatsoever. She would report back to the Sanctuary that the planet was inhabited, and unsuitable for destruction as the creatures that lived on it would fight back. As expected, nobody gave a shit.

At some point, Valkyrie went against Neo-Parshath the Sky Paladin. It is unknown what exactly went down, but the crossover highly suggests that Valkyrie called him a feather-head before engaging in a duel with him. Somehow, Valkyrie escaped with her life; an impressive feet, considering that the Sky Paladin is ten times her size.

Some point after her betrayal, Valkyrie met Celtic Guardian and Performance of Sword, and joined the two of them in their mission to protect to humanity.

Answers
Valkyrie first appears with Celtic Guardian, Astromancy, Performance of Sword, and Gambler of Legend, as they search the Egyptian desert for Dark Magician Girl's egg. She is the one to suggest that they fly through the sand, inadvertently offending a few monsters who are not flight capable.

Ultimately, it is she who finds Dark Magician Girl's egg in the sand. Though unsure as to how an egg would help in a war, she seems to accept that this is happening, and ends up being the first one to have to monitor the egg and wait for it to hatch. Becoming bored of the situation, she leaves the egg with Regulus, not realizing that it is mere seconds away from hatching.

The next time she is mentioned is after Celtic Guardian is banished by Ebon Illusion Magician; in a panic, Valkyrie calls a group meeting between herself, Performance of Sword, and Gambler of Legend. Much to her dismay, she is elected as the new leader of the army, most likely due to her previous military knowledge being a part of the Sanctuary in the Sky. She proves to be of little help, only able to stammer helplessly, before the group are interrupted by Slifer the Sky Dragon.

She is last seen attempting to lead the remains of the army in the final battle, as Obelisk the Tormentor bares down on the timeline. It is revealed that the plan to stall for time by using several hundred Swords of Revealing Light was her own idea. The plan ultimately fails, and Chronomancy and Astromancy are forced to TIMESPLODE the timeline.

What Do You Really Know About This World?
Valkyrie makes her first appearance in the roleplay after Yusei and Yuya explore the strawberry battlefield. Yusei, recognizing Valkyrie's lost sword, decides that she is the best to question about what happened in the warzone.

After stealing her card, Yusei and Yuya summon Valkyrie, and bribe her with strawberry cake made using the strawberries from the battlefield. After seducing her with cake, Valkyrie begins to tell the proswagonists her story, albeit very abridged. She gave Yusei and Yuya the first details about Obelisk, and his ability to reduce worlds to craters, before continuing to mooch off their cake.

Realizing that Liquid Yuto would gladly summon Obelisk, Yusei and Yuya took off, with Valkyrie in tow, to stop him from summoning it and destroying the world. Valkyrie continued to insist that Dark Magician and Celtic Guardian could help in the battle, though the proswagonists would not reply, as no one had seen Celtic Guardian in 5,000 years, and Dank is, well... Dank.

Sensing Yuma's DARK MAJIX, Valkyrie flew away from Yusei and Yuya to pounce on him. Initially, she believed Yuma to be Dark Magician, asking him why he looked different. Her questioning of Yuma was cut short by Astral, who proceeded to assault her with a broom. This proved ineffective, as Valkyrie was able to almost kidnap Yuya, only being stopped by Crystal Wing Synchro Dragon and Number 99: Utopic Dragon.

Insisting that she needed Yuma's DARK MAJIX, Valkyrie proceeded to insult Yuma, pissing off both Astral and Yugo. She was nearly attacked and destroyed, but she was able to teleport at the last second; but not without causing Yuma to begin thinking due to her vague anime shit.

Yuto's SUCH an Asshole
After Liquid Yuto summoned Slifer, Valkyrie was seen again, passing out sunglasses in anticipation for the Winged Dragon of Ra's light effect. Upon encountering Yuya and Yuzu, she was forced to get blue glasses for Yuzu, while Yuya asked her how to defeat Obelisk; Valkyrie replied that she did not know, and that as far as she remembers, '[they] just pouf. Won. Just like magic!'. The mention of magic is what convinces Yuya to ask Astromancy, who informs him of what really happened during the fight with Obelisk.

It's Showtime!
Valkyrie's final appearance sees her running up to Astral before the assault on Yuto's stronghold. Seeing that he has summoned every Number, she joins the monsters in the rush against Yuto's Egyptian Gods and Dark Rebellion.

Abilities and powers
Valkyrie's card effect reads as follows:"When this card is Normal Summoned, if your opponent controls a monster and you control no other cards: You can banish 2 'Nordic' monsters from your hand; Special Summon 2 'Einherjar Tokens' (Warrior-Type/EARTH/Level 4/ATK 1000/DEF 1000) in Defense Position."Valkyrie has yet to be shown special summoning Einherjar Tokens, but she has displayed numerous other abilities. She is an extremely fast flyer, able to keep up with the Yusei Go with little trouble, as well as being able to stop on a dime and change directions while flying, even at high speeds. She is also shown to be capable of teleportation; doing so leaves behind sparkling feathers in her wake.

In terms of fighting, she is shown to use her sword, despite her rather low attack power. She does not regard herself as a fighter, however, and is usually trying to avoid fights with her flight.

She has survived a fight with Neo-Parshath, who, by all accounts, should have easily destroyed her. It is unknown how she accomplished this, and if she actually fought Neo-Parshath directly, or simply fled.

Valkyrie is also shown to have military knowledge, despite simply being a scout; she was able to lead Celtic Guardian's army, as well as quickly construct a plan to hold off Obelisk.

Trivia

 * It is implied numerous times that Valkyrie is associated with Team Ragnarok from the 5D's anime. She is stated to have betrayed the sanctuary due to her love of humans, and in the roleplay, Yusei tells Yuya that he knows someone with her card (likely Halldor) who would not hand it over to him.
 * Valkyrie did not know what cake was, and had never had it prior to Yuya giving her some.
 * Interestingly, Valkyrie's eyes occasionally go completely black. It is unknown if she is merely rolling her eyes in the back of her head, or making her pupils disappear.
 * Apparently, she likes to frighten children by doing this.
 * Valkyrie's insult to Neo-Parshath was revealed in the crossover roleplay. Archlord Kristya mentions that it's a new phrase, implying that Valkyrie was the first person to ever insult the Sky Paladin.