Kallen is someone with a strong sense of duty - like most Kaslanas. Just as her ancestors were ready to give their lives to the fight against Honkai, so was she. Even as a child she was determined to "save the world" from Honkai. When she met Otto Apocaplyse, she recruited him for this cause. As her innocent heart faced the ugliness of Schicksal's corruption, her optimism grew weaker and weaker. Then, when she had to seal the woman she loved, she lost her will to live.