Evil Angelus 95
Total Dork
I've thought more about this (Especially considering that I'm writing a fanfic that deals with the aftermath of S1.), and here are my thoughts.
After Buffy defeated the Master, the realization that she had died sunk in. This caused her to basically go through what is generally called "Post-Traumatic Stress". In order to deal with the fact that she had died, she started repressing emotions, acting differently, etc. She was trying to forget that she had died, and she couldn't do it.
After Buffy defeated the Master, the realization that she had died sunk in. This caused her to basically go through what is generally called "Post-Traumatic Stress". In order to deal with the fact that she had died, she started repressing emotions, acting differently, etc. She was trying to forget that she had died, and she couldn't do it.