User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-16281343-20150721140512/@comment-104.7.80.176-20150721151008

Should be surprised that fafnir kill rizevim, I mean the guy practically begged for his death when he slapped asia which meant either issei or fafnir would have killed him. Would've been better if issei or vali killed him but issei only wanted to save his parents and he promised eariler in vol 18 that vali would be the one to kill him. As for vali, well I guess he knows better than to stand in the way of revenge seeking dragon.