User blog comment:KasuraS/Aldebaran and Ram/Rem's Past Theory/@comment-30772171-20161227072602/@comment-30772171-20161227141753

Yeah maybe Al join the witch cult becuz he know the Archbishop of Sin and they raid the Oni village and somepoint Rem and unconscious Ram that they where surrounded by Cult member but suddenly Roswaal came to the rescue. The Arc 7 will explained maybe why Al hate Ram I guess.