Vivian was a childhood friend of Eason and Leggs. Since she didn't pass the entry test to become a hero fighter she never became Yaga' s apprentice. She served as a private soldier for the dragon temple. The sword she used was given to her by Eason. She sacrificed herself to save Eason from Livermore's attack.
Vivian probably had feelings for Eason because she seemed to care about his health when he won't stop training.
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