Cheong-san becoming the villain in All of Us Are Dead season 2 would be a heartbreaking twist for the zombie K-drama after his sacrifice at the end of season 1. All of Us Are Dead has four lead characters Cheong-san, On-jo, Nam-ra, and Su-hyeok three of whom are safe and sound ahead of season 2. Cheong-sans fate in All of Us Are Dead, however, remains a mystery. While it would be difficult for a person to survive falling from a building as the whole area was being bombarded, there are enough clues to suggest that Cheong-san is alive.

https://screenrant.com/all-of-us-are-dead-season-2-theory-villain-cheong-san-hambie-return/