Bartschius is the Camelopardalis saint of the Century XXI. She is loyal to Athena, but thinks she is Aria, and Mars is an Athena new ally, so, obey his orders.
Her importance in the story is insignificant.
Bartschius was the one of the 3 protector of the Thunder Ruin's guardians... She attacks all the bronze saints, but Haruto decides to fight against her to distract him while Kouga, Yuna, Souma, and Shaina move on. Bartschius is defeated, but survives.
After the war ends, Bartschius goes to fight against Pallas, as a hero that know who is the true Athena. As a good girl, he goes to fight in Pallasbelda.