AboutArachne is portrayed as a calm and intelligent individual. She rarely, if ever, shows any form of distress other than mild irritation; she showed no irritation when Mosquito told her that BREW was damaged in the explosion and left useless (though it was a fake), and even used it as an advantage to trick Shibusen into thinking they still had BREW intact by withholding the true information. Likely due to her abilities, Arachne is not above taking advantage of someone's weaknesses and using it influence them into joining her. She has done this using the Moral Manipulation Machine on Kim and Jackie and later on using her powers to influence Soul Eater Evans.
Arachne also seems to greatly enjoy champagne--the finest vintage. In almost all of her scenes, she is seen drinking one. When she had emerged after 800 years and met with Mosquito, the first thing she asked for was champagne. In the anime, she preferred to drink wine moments after being nearly strangled to death by Asura.
She carries herself in an aristocratic manner, as if she were from a noble stock. This is further supported by the fact that she prefers only the finest champagne. She is almost never seen standing up. Immediately after awakening, she was quickly seen atop a golem watching over the ongoing battle. When she wished to retreat, instead of simply walking away, she was carried off by Giriko. She was welcomed by her butler while walking on a red carpet and is driven by him in a luxurious limousine.
Like her sister, Medusa, Arachne also seems to express particular interest in "madness", eventually becoming madness itself within the Manga. While in the Anime, Arachne is instead allied with Asura but still plans to use madness created by Asura for her own goals.