|Spoiler Alert: This article/section contains details about future plot lines described in the light novels, not covered in the anime. Do not proceed unless you want to be spoiled.|
|“||There is no problem. I understand my sister and I won’t understand each other from years ago.||”|
—Karen Nora Mathers, to Elliot Baldwin Woodman
|Karen Nora Mathers|
|Romaji||Karen Nōra Meizāsu|
|Eye Color||Blue (Light Novel) |
|Relatives||Ellen Mira Mathers (Older Sister)|
|Novel Debut||Volume 8|
|Anime Debut||Date A Live Ⅲ Episode 3|
Karen Nora Mathers (カレン・ノーラ・メイザース, Karen Nōra Meizāsu?) is a member of Ratatoskr and Woodman’s personal secretary, often assisting her boss by helping move his wheelchair. Being a part of Ratatoskr, she has made an enemy of her own sister, Ellen Mira Mathers.
Karen is Woodman’s secretary. Usually, she accompanies her boss to his meetings by pushing his wheelchair. She is also the younger sister of Ellen Mira Mathers, Westcott’s secretary and the world’s strongest Wizard.
Karen has the appearance of a woman in her mid-20s. She is described as a pale Nordic blonde with blue eyes. Her hair is short in length, but she has two front bangs that reach beyond her shoulders. During formal occasions, she wears a formal suit with a small necklace attached. She also wears thin circular glasses. Overall, her appearance is very similar to Ellen, with Shido noting that he has the feeling as if he had seen her before when he first met Karen. She looks older than Ellen despite being the younger sister.
Karen has a very calm and collected personality, often never seen talking when she and Woodman are in public. Unlike her talkative and arrogant sister, she's silent for most of the time, and the few times she speaks are curt one-liners with an indifferent tone. Nevertheless, she is very formal and often handles her secretary duties for Woodman with a professional, yet polite manner.
She is also very loyal to Woodman, often always staying by his side to help him move around in his wheelchair. She is in love with him, following him as he left DEM and openly admitting her desire to start a family with him. Like Woodman, she was relieved that both Tohka and Shido seemed stable, despite the former inversing last month, and the latter summoning an Angel. Also despite her being Ellen’s sister, she agreed that she would be willing to fight the DEM, after Woodman said it might happen in the future. This shows that her loyalty to Woodman is stronger than her familial ties and that she is not as sadistic as her sister.
Karen grew up in the same village as her sister, Westcott and Elliot. When humans fearful of their power burned it down, the four survivors studied the occult while living with Westcott. When the Spirit Formula was performed, she watched from an observatory instead of directly participating like the other three.
Along with her sister, Karen was once a member of DEM's technical staff. However, after Elliot left DEM due to falling in love with the First Spirit, she followed him and became his secretary as he founded Asgard Electronics, and subsequently Ratatoskr. She later reveals that she defected from DEM out of her own love for Elliot.
Powers and Abilities
Like her sister, Karen is one of the few surviving pure Magus. During their childhood, her talent was noted to be far greater than her older sister. Like Elliot, she could sense Westcott recreating the Spirit Formula long before the Spirits did. One year after Westcott's death, Kurumi remarks that Karen is perhaps the greatest Realizer engineer in the world. 
- (To Kotori Itsuka) “I’m sorry for calling in when you are busy Commander Itsuka.” 
- (To Shido Itsuka) “I fell in love with Elliot.” 
- (To Elliot Baldwin Woodman) “——You’re jesting. Isaac isn’t one to think something over much. He is, however, a child who wishes to flaunt his newly received toy to you, his old friend.” 
- Like her sister, Karen’s last name is a reference to Samuel Liddell MacGregor Mathers, one of the founders of the Hermetic Order of the Golden Dawn, which was one of the orders of the Hermetic Qabalah.