Margaret has long, slightly wavy, indigo hair and wears a short-sleeved, long black dress while imprisoned.
Elizabeth points out that she greatly admires Margaret's gentleness and kindness. Like Elizabeth, she believes that the Seven Deadly Sins are the greatest group of knights specially assembled by her father, and that the Holy Knights are the traitors attempting to overthrow the kingdom. However, Margaret appears to be cowardly as the Vivian claimed that she choose to be in prison rather than helping her father like her younger sisters Elizabeth and Veronica. However, it was proved untrue as it was revealed that Margaret was being hold hostage by a creature called Chimera.
In her childhood, Margaret made Little Gil promise to protect her at all times as a knight should to his lady. At some point in time, Margaret gave her earring to Elizabeth on her 16th birthday. When the Holy Knights overthrew her father, King Liones, she was forced to be imprisoned. During the Kingdom Founding Day festival, Margaret oversaw Gilthunder's uncle, Dreyfus and his partner Hendrickson poisoning Gilthunder's father and Great Holy Knight Zaratras, killing him to her horror. Margaret went and told Gilthunder everything about Zaratras to his shock, until they were found out by Vivian who took Margaret hostage by using a Chimera to keep Gilthunder in line and serve the Holy Knights.
Margaret imprisoned in Liones castle
While in imprisonment, Gilthunder came to visit Margaret and report to her that her sister, Veronica, died, to which the latter grow angry at Gilthunder, believing that the Holy Knights were the one who killed her sister. Gilthunder told Margaret that it was the Seven Deadly Sins to which the latter refuse to believe since her father form the group and the Holy Knights are the true traitors and curse Gilthunder for working for them. While imprisoned, she hear Elizabeth calling for her which she respond. Elizabeth found Margaret's cell and told her about Veronica and that she was blaming herself for her death. As Margaret was trying to comfort Elizabeth, the Holy Knight that abducted Elizabeth showed up. She wondered how Elizabeth got out of her cell and also that Margaret is in the cell by her own free will as the latter look away in shame. Elizabeth did not believe that and as the Holy Knight was about to get her, Hawk hit her and protected Elizabeth. As Vivian teleported Hawk away and knocked out Elizabeth, the Holy Knight opened Margaret's cell, telling she will grant Elizabeth's wish and that Margaret is free, as long as she have the courage to escape.
Margaret reunion with Gilthunder
Leaving her cell, Margaret heads outside to see Gilthunder battling his hero Meliodas and begged him to stop while running towards the chaotic battle. When Meliodas used Divine Slayer in Margaret's direction, it turned out that he was aiming for the mysterious creature following the princess saving her life, and resulting in Gilthunder turning against Hendrickson almost immediately. Margaret stood there, lost at the current event and the monster that was close to her. As Meliodas clean himself and walk toward Margaret, the latter ask how Meliodas knew about the monster, Meliodas explain that he realized something was off when they met in Forest of White Dreams and realize what is wrong with Margaret a few moments ago. Meliodas explain that Gilthunder would never compromise his sense of justice if his life was in the line, and realized that Margaret was in danger the whole time. Margaret started to cry and thanks Meliodas for saving them. Vivian ask what made him realize the event, which Meliodas explain that the creed and the way Gilthunder said he was stronger than the Deadly Sins was some kind of code or charm if he was ever in trouble which Meliodas give him ten years ago, and when Gilthunder said those word back in the Forest of White Dreams, he knew he was being watched and someone being taken hostage. After a long battle, Gilthunder stab Hendrickson, unleashing the full power of his Thunderbolt and defeats him and reuniting with Margaret afterwards.
As all the Holy Knights of the kingdom surround Merlin's old castle to bar Hendrickson's escape while Sins battled him, Margaret and Hawk stayed close to Elizabeth's side as the wounded princess is medically treated by a Holy Knight with healing power. When Hendrickson appeared and started to kill the Holy Knights with ease, Margaret wondered why Hendrickson is so interested in Elizabeth which the latter stood up to Margaret shock. As the battle rage on, one of Elizabeth friends, Hawk, was killed during the battle which awake a large light beam that came from Elizabeth. When Gilthunder believe the light to be the after life, Margaret quickly explain that it wasn't, as Elizabeth unleash her true power while revealing that Elizabeth has been unknowingly healing many people in her lifetime. After Meliodas finishes Hendrikcson, Bartra reappears and regain command over the kingdom alongside with Merlin. As the Holy Knights knee for Bartra, the king thanks Gilthunder for protecting Margaret while he was unable to, which led to Gilthunder to request a private chat with the king which Bartra accepted.
While Elizabeth was resting in bed due to not healing herself during the battle, Margaret went to Elizabeth room to check up on her which it was where she met Merlin and when Meliodas step out of the room with a grin which made some of them worried that he did something weird, until it was revealed that Elizabeth is up and healed for unknown reason. Margaret was overjoy to see Elizabeth standing again, but wondered why she is moving again. The next day, Gilthunder bid farewell to Margaret where the two shared a kiss as Gilthunder was quitting the Holy Knights to become a wanderer due to his sins, even if it was just an act.
After the Ten Commandments began their conquest of Britannia, after several months they finally invaded Liones. Margaret remains inside the castle with her father, Veronica and Guila while the Holy Knigts fight against the invaders. When they are unable to stop the advancement of the Commandments, they decide to evacuate the castle. However, two of the Commandments manage to enter and take control of the situation. Margaret stays with Gilthunder, who promises to protect her. However, Gilfrost intervenes by saying that he will not let Gilthunder die, revealing his true identity as Vivian. After asking Margaret not to hate her completely, she teleports away with Gilthunder. After Grayroadwas defeated, Margaret is brought along with the others present in Merlin's Perfect Cube and witnesses the battle and final death of Fraudrin at the hands of Meliodas.
After the knigths could not find Gilthunder, Margaret decides to go and look for it herself. Hendrickson and Dreyfus decide to accompany her.
Margaret becomes Ludoshel's vessel.During their journey, Margaret, Hendrickson and Dreyfus run into a group of demons attacking a couple in the mountains. Margaret tries to confront them, but she is hurt. After Hendrickson and Dreyfus managed to eliminate all the demons, that couple reminded Margaret of her past with Gil and also heard a strange voice in the wind calling her beautiful. During a break, Hendrickson apologizes to Margaret for being responsible for making her and Gil suffer, as well as making Vivian what she is. Margaret, however, admits to feeling angry at herself for being unable to do anything other than being protected by others, thanking both knights for accompanying her on her journey.
Later, Margaret separates herself from her companions when she hears that voice again, which guides her to a Druid Altar hidden in the mountains. Realizing that it was not Gil, Margaret asks her identity to the mysterious owner of that voice. That being tells her that he was waiting for a soul like her's and offers to fulfill her wishes in exchange for her offering her devotion, to which Margaret agrees to save Gil. When Hendrickson believes that she is being possessed by a Demon, he tries to use Purge to save her, however, this is ineffective. There, the mysterious being who had just turned Margaret into his vessel is revealed as Ludoshel, one of the Goddess Clan's Four Archangels.