Rather, I'm going to talk about one of the more curious details of that book. A major non-appearing, historical character who nonetheless plays a major role, is Heinrich Kemmler, a major, monster, master necromancer, who's accused of being the direct proximal cause of both World War I and II, as well as being seen as so dangerous that the entire might of the White Council was marshalled against him alone, as if he were a major supernatural "nation" like the Red Court--and in fact, he was killed at least three times by the White Council, first in the 1800s, at the end of WW2, and most recently in 1961. Is he gone for good? No telling. Good villains are hard to keep down, and he's one of the best--perhaps up there with Nicodemus himself.
Curiously, Heinrich Kemmler is also the name of a major, monster, master necromancer from the history of the Warhammer world as well. Since Jim Butcher is generally pretty clued into geek culture, and since Warhammer is reportedly his favorite roleplaying game (and since Heinrich Kemmler, the lichmaster, features prominantly in several of the old and famous Warhammer modules from back in the day) it seems very unlikely that the names are the same is a coincidence. Heck, it even seems very unlikely that it was accidental, even. More likely it was a deliberate homage.
In fact, when couched in those terms, the use of Heinrich Kemmler as an uber-necromancer from history who's legacy still causes tons of trouble for people in the present day comes across as an example of Yog-Sothothery--the taking of names and details from one story and integrating them into another to give a sense of familiarity. Heck; by now the name Kemmler just sounds like a necromancer's name--because I've heard it used twice as such. So, now--I want a Heinrich Kemmler in my setting. Still trying to figure out where he'll fit in, and I don't have time this week to work it up, but after that, I'm going to actually integrate the idea of Heinrich Kemmler, the master necromancer, into DARK•HERITAGE too, and continue the tradition.