After beating a Griffin dragon with Emily, Yue Ayase and Collet Farandole, the four went to Ostia as representatives for Ariadne. Beatrix is one of the 67 million residents of the Magical World who is pure human derived from Megalomesembria (and hence can be saved by Kurt Godel's plan), as seen when her magic is able to do damage to the demons that attacked Negi's crew during the party held by Godel.
She escaped the ball with Yue and Collette and went on to assist Ala Alba in their efforts to defeat Cosmo Entelechia. She was petrified along with Yuna Akashi and Sayo Aisaka while trying to protect Yue in chapter 310 but she returned to normal in chapter 335.
As a student of Ariadne, she was in the 'Mage Knight' class with her friend and lady-mistress, Emily Sevensheep and was trained in swordsmanship and cavalry combat utlizing broomsticks. She displayed use of ice magic during the Battle at the Megalomesembria Ball
Ice Magic - she used an ice spell to reinforce her Ariadne Greatsword at the Megalosembria Ball when Cosmo Entelechia's magical minions attacked.
TriviaShe looks similar to Shinobu from Love Hina.