User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-77.253.101.192-20141123093720/@comment-24502975-20141124160722

Vritra is a good Evil Dragon, that's why he was sealed into SGs. Splitting someone like Grendel's soul into separate SGs could lessen the negative influence, but it would still be there as a strong risk.