As Yi Chen changed hosts one after another, he grew more adept at the invasion and infection process,
having immersed himself in the assimilation of knowledge for so long, he even discarded the problem of time, and even began to forget his true identity as a human.
Moreover,
Yi Chen also gained a general understanding of the Old World (before it was sealed off) through the memories of his hosts.
The "Source Epidemic Area" could be considered a major power in the human world; patients who came from the Source Epidemic Area were of higher status and even enjoyed many privileges.
Most patients born in the Old World also shared the same goal, to strive tirelessly to be recognized by a Source Epidemic Area, to be accepted as an insider, and to obtain the corresponding illness system.