User blog comment:B214/Question and Answers/@comment-9339850-20130723025527/@comment-1359322-20130723033709

It'll most probably be something like this

Issei + Rias = POD + Dragon power + red hair

Issei + Asia = ???

Issei + Akeno = Holy Lightning + Dragon power + black hair (not really important but i like black hair)

Issei + Koneko = Senjutsu + Youjutsu + Dragon power

Issei + Xenovia = Holy Sword wielder(?) + Dragon power

Issei + Irina = Angel + Devil + Dragon Hybrid (wonder what will happen to the usual weakness of the Devils)

Issei + Ross = Dragon Valkyrie (?)

Issei + Ravel = Phoenix + Dragon (the Immortal Dragon, this feels better than the others)

Ophis is genderless so not sure if she/he can give birth, as for Bennia dunno, after all they're others like Kunou and Kuroka.