I mean, this never really affects their characterization in any official works, and the fandom in question has, for the longest time, primarily been the Japanese fandom. It wasn't the west that turned Yuuka into a sadist in fanon or turned Shiki into a girl insecure about her chest size, etc. etc. All these things happened in the Japanese fanon and we just kind of rolled with it as it radiated out over here into the west. You kinda have to remember that for the better part of 20 years this series has been pretty niche outside of japan, and still kind of is. The Japanese fandom has done most of the "Heavy lifting" for fandom content creation.