User blog comment:Boring12345/What Ifs/@comment-26564607-20150721132811

I remembered Ddraig saying that the Two Heavenly Dragons forgot the reason of the fight between them. Also the fact that God placed them in sacred gears so they can "understand each other".

I think the reason is that they are arguing over "BREASTS and BUTTS".

First: Ddraig's host(Issei) loves breasts and Albion's host(Vali) prefers butts.

Second: Both heavenly dragons had mental breakdowns due to this fetishes of their hosts.

Third: They understood each other because of said fetishes.

So I think that they fought due to this, and God sealed them in sacred gears so they can understand each others *ehem* preferences.