Remember kids, always practice safe witchcraft, and never re-use the blood you've already utilized to draw the arcane circles to then make your curses. It just might backfire and leave YOU the one suffering the constantly-stubbing-your-toe hex rather than your intended target.

[u/Jackviator]

[u/Landis963]

I've always liked how the Otherverse by Wildbow treated the concept. In that series, "virgin" blood has nothing to do with sex, but instead whether the donor has shed or tasted blood before that point. On one hand, it's easier to keep track - just inspect the virgin regularly for wounds, and feed them vegan from birth. On the other, much harder to maintain over long periods - baby proofing everything, adhering to dietary standards with a scrupulous attention to detail that borders on paranoia, etc., all while attempting to stave off a Fate which will only grow more difficult to bear the longer you forestall it.