Sonya

Sonya was a young girl in a Russian village who was killed and impersonated by Grigori.

Plot
She lived there with her father who was her only family. She and her father somehow helped Grigory and in return he made a plot and killed them both. Grigory assumed Sonya's appearance and remained in the village, killing all villagers one by one.

In 1918, the fake Sonya comes face to face with Saya and gets closer with her. However, her true identity is revealed when she kills Roba and transforms into chiropteran form. Saya then kills the impersonating Sonya.