skin tattoo book

Harry Potter Question: the Dark Mark?

I’ve been rereading the Goblet of Fire lately and noticed something that’s been bothering me. On page 645, Voldemort summons death eaters by activating Wormtail’s dark mark.
It says “…[Voldemort] forced the sleeve of Wormtail’s robes up past his elbow, and Harry saw something upon the skin there, something like a vivid red tattoo…”
I know that an activated dark mark becomes dark black (and Wormtail’s does a paragraph or so later), but why is it red at this point in the book? When the dark mark isn’t black, it’s supposed to look like a very faded tattoo… but a red tattoo? Is this because of some exceptional circumstance, or are they always a faded red when not in use?

Hey yeaah! Ive never noticed that.. maybe he had a rash or an allergy.. maybe its cause Voldy is really near him? Im not sure, but intrigued to know the answer anyway
x

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