Faust, she thought no one was around :(

Faust is a talkative, albeit soft-spoken, Sinner with a condescending manner of speech and ineffably high confidence in her intelligence. Despite technically being Dante's subordinate, she often takes the role of their informant and overseer, as she is privy to considerably more information than her fellow Sinners. Because of this, she has a consistent and unwavering faith in her abilities, and does not show any signs of panic even in troublesome situations throughout the first six Cantos. While her expanse of knowledge always proves helpful for the LCB, her egotistical attitude can be excessive. At times, she is outright and unnecessarily contemptuous towards others' inability to keep up with her pace, most frequently Heathcliff, as she appears to lack understanding for those who do not meet "Faust"'s high standards of intelligence. This gives several of the other Sinners moments to criticize her harshness, though she remains steely and steadfast in her ideas, dismissing criticism of her attacks of others.

As one of the more inactive Sinners, Faust frequently prefers to stand back and watch events unfold, often lacking in information she's permitted to indulge, though displaying the fact of lacking knowledge as a place of false certainty. She is kept under the control of the Gesellschaft, a communication network with the Fausts of other Mirror Worlds, which dictates how and when she is allowed to share or access knowledge, among other things. Her inability to access the Gesellschaft connection during Murder on the WARP Express is the first show of vulnerability in Faust, who grows more timid and uncertain as a result. In the face of such hardship, Faust grows self conscious and remains intent on maintaining an indestructible image, even despite her coworkers appreciating the new, more agreeable side of her. Still, she would come to realize the difficulty and uncertainty of a life without Gesellschaft through this event, leaving her with some newfound empathy for those who lack the knowledge she carries.

The Intervallo also makes it clear that, by referring to herself in third-person, she is not always referring to herself, but perhaps another "Faust". As Dante finds, many of her statements come off as considerably less haughty with the knowledge that she is not necessarily referring to herself as an individual. Although she can be strict and dismissive with the other Sinners, this seems to be primarily a result of approaching matters with a strictly logical perspective, rather than any form of ill will, though she will occasionally utilize teaching moments as places to condescend the other party. Her competitive and dismissive relationship with Hohenheim, by comparison, makes it clear that Faust's usual attitude isn't a product of hostility, but rather a constant search towards the factual that butts heads with others doing similar. This also demonstrates that even she is prone to bouts of pettiness; Faust appears to possess many traits and interests that don't benefit the LCB's objectives, such as a love of engineering expanded beyond the creation and maintenance of Mephistopheles. Furthermore, as her relationship with the Gesellschaft is expanded on, there grows an implication that Faust's arrogance is at least in part a result of her trying to compensate for the bullying and degradation she faces for being considered a failure among her peers. The frequent condescension is tied to the innate intelligence of Faust and her Mirror World peers, acting as a defense of character rather than an ontological truth to be conveyed.

Faust has been moderately less secretive about her situation following the incident on the WARP Train, and more understanding of the Sinners' personal wishes and inquiries. Additionally, she appears to have grown more comfortable confiding in Dante about her situation. Although still a know-it-all, Faust now comes off as a bit awkward and self-conscious, painting a more human image of her. Rather than solely using her moments of fact as a place to speak down to the other Sinners, she will sometimes choose to utilize them for learning opportunities, for both herself and others.