The episode in which 你 saw Charlie alive is actually an episode from season 1. 狐狸 never aired it during the first season, and, for some reason, decided to air it in the middle of the 秒 season.
I remember when Olivia shot him in the alley and he died, then all of a sudden he appeared at the office as if nothing had happened. I don't think I've missed anything, but I don't know what happened. Can someone help us, please? :/