"Who exactly are you?" the Pestilence Witch's expression became grave, "A human with strength like yours shouldn't be able to resist my power!"
"A follower of the Goddess of Plague," Xi Mu casually explained, "I am blessed by the Goddess of Plague, impervious to any disease."
He walked towards the door.
"I am here on the command of the Goddess of Plague, to guide you in growing strong enough to become the Goddess of Plague's companion."
The tense expression on the Pestilence Witch's face relaxed, thinking the blessing of the Goddess of Plague made sense.
She followed Xi Mu's steps.
"Human, you say the Goddess of Plague wishes for me to become her companion?"
"Indeed," Xi Mu replied, "The world is about to enter Ragnarok, and the Goddess of Plague plans to find a witch whose power matches her own to be her companion. You are the chosen witch."
A very logical choice.