Isabelle du Monceau de Bergendal (イザベル・デュ・モンソオ・ド・バーガンデール) is a Witch of the 506th Joint Fighter Wing. Isabelle is a small aristocrat from Belgica. When the country fell, she and her family emigrated to Britannia.
Isabelle has short orange hair, kept this length due to being raised as a boy. She wears a large brown coat, under which she wears what appears to be a black scarf with thin white stripes. Perhaps due to her boyish nature, she is one of the few witches who wears spats. She also sports a faded green cap.
Her reckless parents wanted to protect their only heir, so they raised her as a boy named Isaac. This is because they thought that, if she were to be discovered as a witch, she would be considered to be property of Belgica. Due to her having masculine hobbies, such as hunting, she became an excellent shot.
When the Neuroi invaded in 1939, her parents fled to Britannia, with Isabelle fleeing her home amidst the confusion. She volunteered with the RAF whilst hiding her identity, serving as a Pilot Officer, and the flight commander of a Belgican unit. After the liberation of Gallia by the 501st Joint Fighter Wing, she was reunited with her family as the situation in Europe stabilized, however it was also at this time that the RAF discovered her identity. In order to avoid punishment, Isabelle accepted reassignment, and was transferred to the 506th.
Isabelle, who goes by "Isaac" amongst friends, is calm, collected, and has a silver tongue, doing things mainly for her own amusement. This usually includes cracking jokes from old books she's read or playing pranks on the other members of the 506th's A-unit. She appears to be immune to pranks played on her, likely as a result of her experience with them. Even in serious situations, she can't help but joke and tease, seeming to enjoy more the act of telling the joke than the reaction to it, as she once told a joke to an unconscious (and therefore unable to listen) Flying Officer Kuroda. Possibly due to her upbringing, Isabelle seems to have an affinity for cynical and dark humor, once telling an obviously falsified story about an eight-legged goat that cursed her family, making the women unable to eat asparagus without losing their figure. Isabelle is also incredibly intelligent, showing a knack for detective work, as well as being clever enough to easily think up pranks to amuse herself. Despite her teasing nature, she's fiercely reliable, staying on the front lines out of a fear of being seen as a coward. Because of this, she refuses to run from her hardships or troubles, no matter how dire they might seem.
While usually a calm, friendly girl, Isabelle held a considerable amount of animosity and estrangement towards her father for a long period of time. She felt that, despite the concerns he had for her, he had lacked any sort of care for her own desires, forcing her to live a lie in order to hide her identity as a witch. Having read of the bravery of witches, she felt that his decision to raise her as a boy denied her the chance to be who she really was. In her eyes, she was living the life of a coward. After fleeing her country, she decided to become a witch rather than stay with the family that she felt had trapped her. Isabelle's father, unable to understand his daughters choices and fearing for her safety, attempted to end her military career prematurely despite her protests. This resulted in Isabelle growing aloof and distanced from her father, refusing to talk to him even when he would go out of his way to visit her.
Despite the shaky rift between Isabelle and her father, she does still love him. When her father and Kuroda were attacked by a Neuroi, she rushed to save them and was grateful for Kuroda for protecting her father. She even hugged Kuroda as thanks, something fairly uncharacteristic for her. After seeing Isabelle's bravery in action, her father seems to have given his approval, and the two have mended part of their relationship.
While Isabelle is normally very secretive about her past, she feels strangely comfortable confiding in Kuroda, even going so far as to tell her things she'd never told another person before. Even Isabelle doesn't fully understand the reason for this, though it's possible that she simply enjoys confiding in someone who doesn't act like the nobility she's used to.
Isabelle has a wealth of seemingly random information, exhibiting a strong ability to retain such information. She once listed off extensive statistics about a baseball player from Flight Lieutenant Carl's hometown, acquired solely from a book she'd once read as a child. Books seem to be where she gets most of her information, as she enjoys reading from a wide variety of sources and genres. Some of the more notable examples include detective novels, witch history texts, and even issues of Vogue magazine.
Isabelle picked up many hobbies as a child, most notably hunting, which has made her an excellent shot. However, she also has more traditionally refined hobbies, and enjoys playing the piano.
One of her most notable skills is her persuasive speech. Isabelle is incredibly charismatic, and, according to Flying Officer Kuroda, it's difficult to tell when she's serious or not due to her incredible poker face. This has led to her tricking various people (mostly the aforementioned Kuroda) into her pranks, such as when she managed to convince Kuroda that a rich noble was rewarding her with money when she worked hard. In reality, this was Isabelle herself making small "donations" in order to see how much work she could get Kuroda to do. In another instance, she managed to sic Squadron Leader Wittgenstein on multiple people during an investigation, accomplished merely by mentioning Wittgenstein's keen senses after the Squadron Leader began suspecting anyone who entered the room.
- Strike Witches Movie (unnamed cameo)
- Her familiar is the Bouvier de Flandres.
- Interestingly, the Bouvier de Flandres is almost always black or brown, and even members of the breed with a white coat generally have black ears. Isabelle's familiar notably has white ears, though due to her noble status it's entirely possible the dog was just bred very selectively.
- She is based on Yvan Georges Arsène Félicien du Monceau de Bergendal.
- Isabelle's original backstory differed slightly from her current one, with her being a witch before evacuating Belgica and reorganizing a Belgican unit once in Britannia. It also lists her reason for joining the 506th as Britannia panicking to send a representative to the unit, rather than her being forced into reassignment due to her identity being discovered.