Isaac Ray Westcott is the managing director and de facto leader of Deus Ex Machina Industries, a powerful corporation that develops Realizer technology. He is a tall man with dark ash blond hair and sharp, penetrating eyes, giving him a somewhat predatory appearance. While he looks to be in his early thirties, his actual age is significantly older, potentially around fifty or more, a discrepancy that adds to his mysterious and unsettling presence.

Westcott was once a resident of a village of pure mages, where he grew up alongside Elliot Baldwin Woodman, Ellen Mira Mathers, and Karen Nora Mathers. His early life revealed a deeply ingrained morbid fascination with death, as he derived a sense of pleasure from witnessing suffering and mourning, an instinct he learned to conceal. The pivotal event of his youth came when ordinary humans, fearing the mages' power, burned his village to the ground. While his companions were horrified, Westcott felt a sense of liberation and even gratitude, as the destruction removed the social constraints that had forced him to hide his true nature. This tragedy provided him with a convenient justification for his ambitions.

Following the destruction of his home, Westcott was adopted by a wealthy couple and later inherited their fortune. He used these resources to co-found DEM Industries with Woodman and the Mathers sisters. Driven by a desire to reshape the world, Westcott dedicated himself to the study of sorcery. Roughly thirty years before the main events of the story, he, Woodman, and Ellen successfully performed the Spirit Formula, a ritual that gathered all of the world's mana into one point. This ritual created the First Spirit and, as a catastrophic side effect, triggered the first major spacequake, which devastated a large portion of Eurasia. While Woodman eventually had a change of heart and founded Ratatoskr to protect Spirits, Westcott remained committed to his original plan, leading to a bitter schism between them.

Westcott's personality is defined by a profound and unsettling sadism. He is exceptionally intelligent, calculating, and patient, capable of orchestrating complex schemes that span years. His cruelty is not simply a means to an end but a source of genuine enjoyment. He demonstrates a complete and utter lack of empathy, viewing virtually everyone, including his own loyal subordinates, as disposable tools to be used and discarded for his goals. He is a master manipulator, able to wear a mask of civility and charm when necessary, but this facade thinly conceals his utter contempt for others. He has a particular fondness for psychological torture, often offering his victims false hope before cruelly crushing it to maximize their despair. This was evident in his treatment of the Spirit Nia Honjou, whom he allowed to temporarily escape and find happiness, only to shatter that happiness to force her into a state of inversion. At the same time, Westcott can display a certain childishness, deriving amusement from his powers like a child with a new toy. His mindset is described not merely as cruel or brutal, but as fundamentally abnormal.

Westcott's primary motivation is the annihilation of the current human race and the creation of a new world. While he often cites revenge for his destroyed village as his reason, this is largely a pretext. His true drive is a deep-seated, innate desire to inflict suffering and reshape existence for his own amusement and satisfaction. To achieve this, he seeks to harness the immense power of the Spirits. His specific method involves forcing Spirits into their Inverse Forms to extract their Qlipha Crystals. He then absorbs these crystals to gain the powers of their corresponding Demon Kings, bringing him closer to his goal of rewriting reality.

As the driving force behind DEM Industries, Westcott serves as the primary antagonist throughout the story. He is responsible for many of the direct conflicts the Spirits and Shido Itsuka face. He demonstrates a keen interest in Shido, recognizing his unique ability to seal Spirits' powers and referring to him by his original surname, Takamiya, indicating deep knowledge of past events. He has orchestrated numerous attacks and capture operations, including an attempt to force Tohka Yatogami into inversion by threatening to kill Shido in front of her. He is a shadowy puppeteer, pulling strings from behind the scenes, but is not afraid to take direct action when the moment is right.

His key relationships are defined by utility and a shared, albeit twisted, history. Ellen Mira Mathers serves as his supremely loyal secretary and bodyguard, the strongest Wizard in the world. Her devotion to him is absolute. Elliot Baldwin Woodman is his former friend and collaborator, now his greatest rival and the head of Ratatoskr. Westcott views Woodman's defection as a betrayal but still expresses a desire to have him return, revealing a complex connection to his past. His relationship with Shido Itsuka is one of direct opposition, as Shido represents the only real threat to his plans, a fact Westcott acknowledges and even seems to appreciate on some level.

Over the course of the narrative, Westcott's power grows significantly. Initially relying on Ellen and DEM's resources, he eventually succeeds in obtaining a Qlipha Crystal from the Spirit Nia, gaining the incomplete Demon King Beelzebub. This Demon King takes the form of a large black book and grants access to vast amounts of information, allowing Westcott to uncover hidden truths. It also allows him to summon shadow-like creatures known as Nibelcole to fight for him and to trap targets in a fantasy world called Ashufiriya. Later, after losing Beelzebub, he performs the Spirit Formula on himself, becoming the Second Spirit of Origin. In this form, he wields immense power comparable to the First Spirit, with Demon Kings that mirror her Angels. His abilities include a nearly impenetrable defense, the power to empower his followers, and various reality-altering attacks.