User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-65.8.85.249-20140620230159/@comment-24501441-20140621022829

In response to the OP, and this is just speculation, but maybe the FHB (as JJJ calls him) sees Issei and Sairaorg the same way...young devils with little to no aptitude for magic who both work very hard for their dreams (something described as being new in the world of devils). They've both become heroes of the underworld, and the FHB could see them as the next step in the changing world of devils...Old Maou faction -> new Maou- > Issei/Sairaorg. But I do agree that Issei's probably not gonna be a Maou.