User blog comment:B214/General Discussion/@comment-27083298-20170518013300/@comment-31137559-20170528074444

I was thinking it would be Saji due to him loathing Issei for dating his master while Saji can't even get Sona to call him by his first name. Remember how Saji was the final boss for that game Ajuka and Azazel made that Issei ended up participating in and also Sirzechs and Serafall were with him?