Prince Renathal

Him being shirtless, the almost white blond hair, the sentient flying sword, and him being the son of a vamparic evil father who he has to fight against, all give me strong Alucard from the Castlevania anime vibes lol. Perhaps he is a reference?

He has some of my favorite dialog this expansion, his farewells are the best
"There is no possibility of victory... how is that not exciting?"
"You and me against the end of reality... we might need some help..."
"We are doomed... but not without a fight"

After the quest Blinded By The Light has been accepted, players are able to interact with Prince Renathal and he will give a short history of Sinfall:

Sinfall.

This is where Denathrius sired his first Court of Harvesters, ages upon ages ago. Here he forged the medallions so that we each may share a piece of his power and carry out his will.

There was symmetry to him exiling me to the Maw in this place. He believed he was ending me where he created me.

Now we shall use this place to turn the tide against the Master of Revendreth and undo his very grip upon this realm he created.