Revenge
S1, E28: Al-Fadl bin Al-Sahl kills Harthama with poison, angering Al-Ma'moun and causing him to remove Al-Fadl from his position; Al-Fadl takes revenge on the Caliph by killing Ali bin Musa and blaming it on Al-Ma'moun; in turn, Al-Ma'moun kills Al-Fadl.
