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You would be shocked to learn then that Hitler is intensely interested in magic and 'the occult'. He has researchers looking into ways to use the supernatural to benefit him. I used to know a ghillie dhu who was forced into servitude by Nazis along with a number of others. They called them 'Der Kobold' - nevermind what species they were.
You would be surprised what people will do to save their own skins - much like the German population. A great number of them don't agree with the Nazis but they're far too afraid to say anything about it.
How to explain this without bringing up the multiple worlds-- There are... Subtypes of vampires. Some require an invitation. Others do not. I would not, for example, and not because of my age.