She is voiced by Hitomi Nabatame in the Japanese version of the anime, while in the English version she is voiced by Janyse Jaud in season 1 and Colleen Clinkenbeard in seasons 2 & 3.
Margery has very long blonde hair, which is usually tied up in a neat, high ponytail. She has blue eyes and wears spectacles. In the anime series, she is 173 cm tall, and she appears physically to be over 20 years old. She is quite well-endowed.
Upon arriving in Misaki City, Margery was shown to be cold and ruthless even by Flame Haze standards, being fueled by deep hatred for all Crimson Denizens. Unlike most Flame Hazes, she didn't even care about preserving the balance, hunting Denizens purely out of spite and even picking fights with other Flame Haze for fun. To her, there was no such thing as an innocent Crimson Denizen and she was perfectly willing to kill Denizens who were causing no harm to the balance, such as Lamies. She was also shown to be violent and abusive towards Marchosias, often hitting him and calling him "stupid Marco" (baka-Marco) when he made fun of her, something that's never been done by any other Flame Haze.
Margery is shown to be extremely skilled in combat and creating unrestricted spells. However she also has a serious drinking problem and tends to consume as much alcohol as she can until she passes out (according to Marco, her tolerance for alcohol is the same as any normal person's.)
Margery prefers to be alone in her missions, until such time that she met Eita and Keisaku. At first, she thought to dispose both of them just as easily but their persistence and admiration (probably affection in Keisaku's case) for her led her to have a soft spot for both of them. She eventually warms up to more characters in the series (particularly Shana, Keisaku, Eita, Wilhelmina and Yuji). After the disappearance of Yūji, Marchosias notes that Margery is now somewhat used to the idea of having teammates, due to the fact that she's even training Shana in battles.
Overall, Margery is very much a person guided by her emotions and little else; when she mistakenly believes the SIlver to have appeared, she goes on a roaring rampage in an attempt to get her revenge, completely ignoring the current problem. Tragically, Matake Ogata is temporarily killed as a result of this, the sight of which completely destroys Eita's initial view of her. She repairs the damage she caused afterwards, but the damage to Eita's soul has already been done, and from then on he can barely stand Keisaku even mentioning her. Despite this reckless nature, Margery shows on occasion that she is more than capable of being logical, such as when she scolds Yuji for getting ahead of himself and requesting training he's not ready for. She is also a wise and mature woman in regards to love, as shown when she gave advice to both Kazumi and Ogata about their feelings of jealousy and how things aren't always what they seem. Amusingly, she is also a ready listener to the woes of others, which leads to her drinking pal friendship with Wilhelmina, who would share her concerns and frustrations over Shana's development in the company of Margery, Marchosias and much alcohol.