
What did Ansem The Wise do to make them 'Norts that mad?
Apprentice Xehanort stole his identity and wrote fake reports in his name.
Xemnas was clearly still angry over Ansem denying his research into the Heart.
Ansem Seeker of Darkness committed actual identity theft and then had the gall to roll up on the actual Ansem and call him "master" like they were still cool.
What did he do?