Signing in with google for the first and maybe last time ever (idk) to chip in my own 2 cents.
http://www.giantitp.com/comics/oots1007.html
Vampire!Durkon was made by Hel to fill and embody the deepest, darkest parts of Durkon.
Sure, the part has resentment of the dwarves and such in it, but do you know what else it has, according to this strip?
It has all the repressed feelings about freedom and happiness in it - and love for Hilgya, apparently. Love for Hilgya and everyone else.
Durkon, by showing this memory, is forcing the vampire to be more like him - and it's
working, judging by the fact that Vampire!Durkon is stunned silent and uses "Tha" in panel 2.
On top of that, Durkon's still silent. The fight's not over yet.