I wonder if Dwight Renfield is supposed to be a renegade member of the "True Knot" from Doctor Sleep. The description of those vampires and him plus their MO are very similar.
If my answers frighten you then you should cease asking scary questions.
I think they are two species under the same order, kinda like It's relation to Dandelo(King hinted that both are similar creatures, but whatever It is, it's far more stronger than Dandelo's race). King has many different types of vampires in his stories. Kurt Barlow's considered one of the more powerful types of ancient vampires, and his type(among others seen in the Dark Tower series) are far different(and kinda more traditional) than the True Knot and Dwight Renfield. There's also Skinner Sweet(from American Vampire), who is immune to sunlight and has Pit Viper/Rattlesnake fangs.
Both the True Knot and Renfield share the "single growing fang" look, as well as stretching mouths and an existence roaming the country for victims, that's the most of it. Renfield is more classic vampire, choosing to travel in the night, feeding on blood and having to sleep within the dirt of his grave. The True Knot, to my knowledge, can travel in daylight, feed on the "steam" of special victims(children with the Shining ability) and sleep like regular people(and in most cases, do things many normal people do, as many of them can blend into society).
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