Vivian/Plot

Kingdom Infiltration arc
When the Seven Deadly Sins discusses why the Holy Knights are focused on targeting Elizabeth in the Boar Hat, Vivian reveals herself by telling them that the princess of Liones is the last remaining key of the Coffin of Eternal Darkness to release the Demon Clan before teleporting herself with Elizabeth, and unknowingly Hawk to the kingdom. Her actions greatly angered Meliodas as he and his fellow Sins Ban and Gowther immediately launched a risky rescue attempt to save Elizabeth only to face the entire Liones' Holy Knights. Later when Elizabeth regains consciousness in a cell, Vivian welcomed her back to the kingdom before teleporting away. At some time after discovering Elizabeth's escape, she teleported before Hendrickson and reported the situation while noticing King Arthur Pendragon of Camelot and his cloaked friend being surrounded by the Great Holy Knight and his subordinates. After receiving orders to recapture the princess and relocate her to a place where the Sins cannot reach her, Vivian bade farewell to the young king before teleporting away again.

Shortly afterwards, Vivian finds Elizabeth near Margaret's cell, informing her that the First Princess allowed herself to be imprisoned due to her cowardice when she was accused by Elizabeth and attempted to take her only to be pushed back by Hawk. Seeing a talking pig in front of her, she expressed disgust and teleported Hawk to the Horn of Cernunnos telling him to disappear, which knocked Elizabeth unconscious. Vivian then allows Margaret to leave her cell granting her captive's wish of her sister's freedom, if she has the courage to do so. She then contacted Hendrickson that she recaptured Elizabeth and was given orders to keep the princess away from the Sins as possible. She asked permission to aid Hendrickson but the latter refused, then she gave in and informed him that she'll be sending her cute little knight to aid her superior in battle against Meliodas.

Taking the princess to the king's heavily guarded chambers, she allows a brief father-daughter reunion as Elizabeth and her father before proceeding with the ritual. She decides to observe the battle noticing Gilthunder seemingly overpowering Meliodas and telepathically compels him to kill the Seven Deadly Sins he once admired. Suddenly Slader, captain of Dawn Roar, appears before the doors of the royal bedchambers, demanding an audience with the king. Slader forces his way to the door which was protected by Perfect Cube. Noticing that Slader was injuring himself, Bartra begs him to stop. Vivian decides to observe Meliodas' battle against Gilthunder and was surprised to discover that Meliodas was overpowering Gilthunder. When Vivian mentions Meliodas' name, Elizabeth grows happy as Meliodas had come to save her. Vivian tells Elizabeth not to get too happy as Meliodas will be defeated soon, but Elizabeth tells her that Meliodas will not loose. The battle gradually grows more and more intense, leading Vivian to head out to the battlefield and help Gilthunder and Hendrickson. As the battle continues, she readies herself besides Hendrickson and Gilthunder to battle against Meliodas.

As the trio start to overpower Meliodas and knock him into to a building, Vivian is amused that Meliodas is mortally wounded as he has not used Full Counter or his Demon powers, but Gilthunder sense that Meliodas' power is increasing instead of decreasing. Hendrickson says that they have miscalculated and know where the eerie premonition came from. Hendrickson finds out that the reason for Meliodas not fighting back was because Meliodas was heightening his power and senses to their utmost limit to unleash a one decisive attack. The Holy Knights used all of their powers together to finish off Meliodas before he could unleash his attack. Hendrickson, Gilthunder and Vivian attack all in unison as Meliodas prepares his own attack. However, Margaret comes running toward the battlefield to stop Gilthunder from hurting his hero, Meliodas. Meliodas spots something close to Margaret and used his Kami Chigiri to kill an invisible creature that was next to her. As Meliodas grinned about destroying the creature, Vivian's attack hit Meliodas, heavily injuring him. As Hendrickson rushed towards Meliodas to finish him off, Gilthunder appeared and cut off Hendrickson's arm. Gilthunder, with a tear in his eye, smiled and thanks Meliodas for setting him free from the spell as Meliodas smiles back.

Vivian was in shock to see Gilthunder betray Hendrickson until Meliodas explained how he knew about Gilthunder being forced to work with the Holy Knights and Margaret being held hostage. Vivian asked what made him realize the event, to which Meliodas explained that the creed and the way Gilthunder said he was stronger than the Deadly Sins was a kind of code and charm for if he was ever in trouble, which Meliodas give him ten years ago, and when Gilthunder said those words back in the White Dream, he knew Gilthunder was being watched and someone had been taken hostage. Vivian found it to be an absurd lie, as he was fighting against Gilthunder in an all out battle, but Meliodas pointed out that Gilthunder put his life on the line for the woman he loved, and he put his life on the line too, as it is how friendship between men works.

As Meliodas' group heads to the castle to rescue the king and Elizabeth, Vivian teleports the group into a forest. King attempts to fight Vivian, but Vivian returns to Liones, leaving the group to be lost in the forest forever. Much to the group and Vivian's amazement, the group are also teleported back to Liones, thanks to a mysterious cloaked friend of Arthur. Vivian is suddenly teleported to a dragon's nest, a waterfall, and various other locations. Eventually, the cloaked figure stops toying with Vivian, and an enraged Vivian attacks the cloaked figure with winds. In spite of the winds, the cloaked figure is unharmed, scolding Vivian, her apprentice, for losing her temper. A shocked Vivian sees a crimson pig tattoo on the cloaked figure's neck, and the winds vanish, revealing the uncloaked person to be Merlin of the Seven Deadly Sins. As Merlin teleport the group to the Royal Chamber to free Elizabeth and Bartra, Vivian laughs, believing that there is nothing Merlin can do to free them until Merlin used Absolute Cancel and erase Perfect Cube to which Vivian finds it cheating. Vivian tossed her helmet in defeat and start crying, as she lost control over Gilthunder until Hendrickson appear as he reattaches his arm and told Vivian she can have him back and the party isn't over yet.

When Hendrickson went off to awake the Demon Blood in the New Generation to create hybrid Demon, Vivian was waiting for Hendrickson order to attack. Once Hendrickson went to the Deadly Sins and Holy Group, making King fight against the enslave Helbram. Meliodas and Gilthunder went off to fight Hendrickson until the latter who summon Vivian to take Elizabeth and Margaret hostage. As Vivian was taking the two princess hostage, she told Gilthunder that they could be together and never leave her until Hendrickson ends up stabbing Meliodas and Gilthunder when their backs were turned to Vivian's shock. Vivian asks about their promise until Hendrickson explain that Gilthunder will never leave her if he is a corpse to her shock. However, Elizabeth stood up and ask to be taken to spare Gilthunder and Meliodas life to Vivian shock.

Still grieving for Gilthunder's life in danger, Ban picks up Holy Knight Gilthunder and threw him at Jericho in Demon form to knock her down and save Diane much to the girls' horror but were relieved when Ban used the Incantation Orb to heal Gilthunder and Diane with a Hyper Recovery Spell.

Later when all the Holy Knights surrounded Merlin's old castle to bar Hendrickson's escape while the Sins dealt with him, Vivian joins them although hid behind Gilthunder and Guila shyly.

Once Hendrickson was finally defeated and peace restored Vivian was seen spying on both Gilthunder and Margaret and crying as they kiss.

Signs of Holy War
In the days following Hendrickson's defeat, Vivian was secretly following Gilthunder without him noticing. However, Merlin is able to perceive her presence, so she asks Meliodas to take charge. When Vivian places a love potion on Gilthunder's tea, Meliodas intervenes revealing the presence of Vivian. Enraged, Vivian tries to attack them, being easily defeated by Meliodas's Full Counter.

Vivian is then held in Merlin's laboratory, using special chains to nullify her magic. There, Merlin asks Gilthunder to decide Vivian's fate after what she did to him and Margaret, but Gilthunder decides not to punish her. Even so, Merlin uses her Curse Engage to curse Vivian and thus causing extreme pain and finally death if she does any wrong against Gilthunder.

When Merlin reprimanded her for helping Hendrickson to release the Demon Clan, Vivian claims that they could have controlled them with weapons like the Goddess Amber. There, Merlin states that Goddess Amber can only enclose low-level demons like the Red Demon or Gray Demon, revealing the existence of much more powerful demons within the clan, which causes Vivian to burst into tears.

Great Fight Festival arc
With Diane, Gilthunder and Howzer struggling against an Earth Crawler, Vivian, disguised as a magician named Gilfrost, appears and uses Freeze Coffin to help them eliminate the creature. Upon arrival at the end of the maze, Drole and Gloxinia force all those who are present to participate in a fighting tournament; Gilfrost is partnered with Gilthunder and set to fight Silver and Quazzo.

During the battle between Gowther & Jericho versus Escanor & Hawk, Escanor deceives the two Ten Commandments and injures them. Meliodas quickly takes advantage of the opening and attacks his former comrades, prompting Drole to trap all the other participants and use them as hostages. Imprisoned beneath the earth, Vivian volunteers to try teleporting everyone to a safe location, successfully arriving at the Kingdom of Liones. She discusses that the Ten Commandments should not have been awakened, but suggests that Meliodas terrifies her far more because he has already defeated Drole and Gloxinia. When Meliodas is overtaken by the Ten Commandments, Elizabeth asks Gilfrost to teleport him with them, but Gilfrost explains that she would have to go there herself to do so, something the Ten Commandments would never allow. Gilthunder ask to be teleported with Meliodas instead, but Gilfrost refuses to send him to his death. Gilfrost witnesses with all the others the death of Meliodas. He later sends Elizabeth to Vaizel in search of Meliodas's body.

Defensive Battle for Liones arc
Gilfrost is present along with the other Holy Knights when the Ten Commandments invade Liones. After they were all cornered by Grayroad and Fraudrin, Gilthunder tells Margaret to stay by her side no matter what. However, Gilfrost intervenes claiming that he would not let Gilthunder die, revealing his true identity as Vivian. She then teleports along Gilthunder outside the battlefield.

For days, Vivian kept Gilthunder locked up with her in a secret spot that only she knows. Gilthunder demands to Vivian return him to Liones, but she says that all of Liones must have been killed by the Ten Commandments, including Margaret. Gilthunder decides to use the curse that Merlin had put in Vivian to force her to free him, but Vivian affirms that they would remain in its small kingdom with him like the king, and she like his slave.

Prelude to the New Holy War arc
When Gilthunder finally finds a way out of the building where Vivian kept him, he finds out that he is in a temple high in the sky. Then Vivian appears and states that there is no way for him to leave that place built by the Goddess Clan. Gilthunder affirms that he wants to be with Margaret to which Vivian affirms that Margaret and all Liones must be dead and that they would have died as well had they not escaped. When Gilthunder tells her to shut up, Vivian declares that they must continue living for Margaret and that they can even have a daughter and name her after the princess. At that moment, a portal opens behind Vivian, from where Ludociel, after having taken Margaret's body, comes out and pierce Vivian's throat with his sword.

Demon King arc
Gilthunder and Howzer are having a toast with Griamore in his house, to celebrate the victory of the Sins. Howzer wonder what kind of era will come with the gods gone, to which Gilthunder hopes it will be an era of peace. However, Vivian suddenly appears saying that when the balance between light and darkness is broken, an era of chaos will come.

Gilthunder and Howzer get alarmed by Vivian's presence. Gilthunder says he thought that Ludociel had killed her. Vivian claims, in a rather delusional way, that thanks to Dreyfus and the power of love she was brought back. Gilthunder clarifies to a confused Howzer that Dreyfus begged Hendrickson to heal Vivian, and Griamore adds that his father couldn't bear to leave wounded and alone either, so she ended staying in their house. Vivian also reveals that the curse that Merlin put on her was dispelled as well.

Vivian then tells Gilthunder that they are "breaking up" since her eyes opened to true love. Gilthunder then asks what she meant by an "era of chaos", to what Vivian responds it was something that Merlin always said.