There is power in blood, that was something Harry Potter was intimately familiar with and he never doubted it. However, what happened definitely surprised him. It started on a mission for the Order, him and Fleur were looking for one of Voldemort’s artefacts. The hideout was not guarded by men and the traps were quite easy to detect and dismantle.
Too easy, it turned out. There was a guardian. A demon from nightmares suddenly charged at them, a thing of shadow and flame, of curse-bound flesh. Though dodging the cat o’ nine tails made of cursed flame and the sword of lightning and thunder was far from easy, they managed, and eventually, their spells managed to pierce its hide and . As the beast crumpled to the ground, Harry and Fleur stood panting, supporting each other. They certainly did not expect it to explode.
Fortunately, they both woke up quickly, healthy and whole, however, they had a particularly nasty feeling in their mouths. When the demon blew up, some of it ended in their mouths and they reflexively swallowed.
As they would find out, partaking in demon flesh and blood, especially of a demon they slew together, would have consequences.