Grandpa
After a few hours of staying in the space, Mo Li and Fang Yu decided that it was best to help the humans in this war. Of course, they weren't planning to involve the rest of the sect. It was decided that the sect would change its base into the secret space.
After a few more days of staying in the space, Mo Li and Fang Yu finally left and went back to the human world. Using Fang Yu's expertise in potioneering, it was easy for her to create some medicines that were able to counter the diseases that the devils used against humans. Of course, this had something to do with the fact that Mo Li was a very old demon. He was practically someone who has lived a long— long— long life. While Mo Li never really told her his real age, she guessed that the man might have probably traveled to different worlds with different times, meaning, he could be older than ten thousand years old.
With his age, comes a lot of knowledge from different worlds.