User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-26865730-20150809032309

I wonder where Belial got the dragon's blood? I mean it had the effect of revealing his dragon nature to Issei's parents but it also gave him a boost in dragon power right before he was going to need it for the serious beat down to come.

I wonder if it came from Tiamat when the Emporer met with Ajuka and Tiamat? If so, then he probably would have told her its intended purpose and they would have known that blood from a dragon king level being would have a definite effect. So is what he was really doing was slipping Issei a power-up right in front of Rizevim?