They try it the ordinary way first, because they are not idiots, and because Mione insists on ruling out the boring answer.

Mione pricks her thumb with the bone pen and squeezes four drops into the bowl. Malfoid does the same. You do the same.

The ink sits there. The pen goes into it and comes out brown and writes on the folio and the folio does not take a mark.

MalfoidNothing. Two hundred years of my family swearing on a man and he will not take our blood.