I will get to the main point real quick. I was speaking with a friend about the history of the grey host, along the way we started to speak about the volkihars and harkon, and serana, and i mentionned that serana was using in skyrim the breton model, but harkon was using the nord model along with valerica. This thought made me actually wonder :
is the volkihar FAMILY an actual nordic family ?
I don't have a lot of evidence, to say none, but mostly hints.
To begin with, when you free serana from the crypt, she mentions two things :
1- When she was imprisonned, cyrodiil was NOT the seat of an empire, which says that she was imprisonned before the birth of the alessian empire in 1E242.
2- She asks the dragonborn "who is the high-king of skyrim", which says that at the time she was imprisonned, nords were already there, and organized as jarl voting for a high king.
So, she was imprisonned after the arrival of Ysgramor, at the very least, and the birth of the alessian empire. Ysgramor arrived in skyrim in the late merethic. Moreover, in skyrim, kodlak says the Companions are "nearly 5000 years old", which would indicate that the Return occurred sometime in the last five centuries of the Merethic Era.
If i'm not mistaken we have therefore a 700 years time period in which serana was imprisonned wich is consistent with what is said in
this Q&A.
But then, what about the birth of the volkihar family ?
It is said that they are nords, but there is something that bugs me in this explanation.
First, Harkon, when talking about himself, says that "
In an age long forgotten to history, I ruled as a mighty king". He does not say "Jarl", as a nord would normally say, he says "King".
One explanation would be that he had been the High-King of skyrim, but he does not say it.
He does not say that he once "Ruled over skyrim", he says "
My domain was vast, my riches endless and my power infinite".
Why ?
Moreover, serana asks us who is the high king of skyrim now, which she would probably not if his immortal and all-mighty father was. So what is harkon the king of ?
The answer that i find most satisfying and realistic is that they are actually ancient nedes, like Lamae Bal. More then that, the name "Harkon Volkihar" does not sound that nord, when you think about it. but i find it closer of "Lamae Boelfag" which was the nedic name of Lamae Bal.
As a conclusion, i do think that Harkon Volkihar pledged himself to molag bal and became a vampire lord, along with his wife and daughter when he was a nede king, ruling over what will become centuries later the skyrim we know.
Edit to add sources used :
About serana and her dialogues
https://en.uesp.net/wiki/Lore:Seranahttps://en.uesp.net/wiki/Skyrim:Serana
About the time she was imprisonned
https://www.elderscrollsonline.com/en-us/news/post/699
About Harkon and his dialogues
https://en.uesp.net/wiki/Skyrim:Lord_Harkonhttps://en.uesp.net/wiki/Lore:Harkon
For the time of Return
https://en.uesp.net/wiki/Lore:Merethic_Era
For the birth of the Alessian empire
https://en.uesp.net/wiki/Lore:First_Era