User blog comment:Ariel Saeba/Mythology and Character Origins in DxD/@comment-50.139.232.230-20160328020654/@comment-27876048-20160330031757

Thought I'd give some sorce material if you want to research further.

https://en.wikipedia.org/wiki/Lludd_and_Llefelys

https://en.wikipedia.org/wiki/Welsh_Dragon

As a side note the material above is just some of the versions of the story because as you know mythologies tend to have multiple versions for each story. Also because the Welsh Dragon (i.e. Ddraig) was the mascot/symbol on King Arthur's standard/banner, as well as other celtic kings, I find it kinda funny that Le Fay (King Arthur's female descendant) will have a son with Issei, as was revealed in High School DXD Ex.