Science Fiction & Fantasy Stack Exchange is a question and answer site for science fiction and fantasy enthusiasts. It only takes a minute to sign up.
Sign up to join this community
Polyjuice Potion is changing based on someone's current physical state. It shows tattoos (or lack of) and such from DH when Ron changed to Harry.
"I knew Ginny was lying about that tattoo,” said Ron, looking down at his bare chest.
What would happen if someone used hair of a dead person, taken from their body after death, and drank the potion? Would they die as well?
Unclear.
Then I packed up Moody’s clothes and Dark detectors, put them in the trunk with Moody, and set off for Hog- warts. I kept him alive, under the Imperius Curse. I wanted to be able to question him. To find out about his past, learn his habits, so that I could fool even Dumbledore. I also needed his hair to make the Polyjuice Potion.
He states that he kept Moody alive to question him so he is able to fool Dumbledore.
This line is unclear as to what it targets,
I also needed his hair to make the Polyjuice Potion.
You can read this line as saying, "he needed Moodys hair", "so he put his body in the trunk", OR you can read this line as," I needed Moody alive so he kept growing hair that i could use for the Polyjuice Potion".
Neither option specify that the Polyjuice Potion NEEDS a living victim for the potion to work. That is pure speculation on our part via the text.
Its important to note that Barty Crouch Jr. needed a supply of hair for an entire school year, of potentially drinking the Polyjuice Potion every hour of every day. So would you risk just shaving his head and killing him, what would happen if you ran out of hair? Hence keeping him alive, to continue to GROW hair would be important.
Simply because Barty Crouch Jr. kept Mad-Eye Moody alive in order to use his hair for the Polyjuice Potion. BCJ is not a nice man; he would presumably have killed Moody if he could rather than imprisoning him. He needed him alive for the Polyjuice.
"I kept him alive, under the Imperius Curse. I wanted to be able to question him. To find out about his past, learn his habits, so that I could fool even Dumbledore. I also needed his hair to make the Polyjuice Potion. The other ingredients were easy. I stole boom-slang skin from the dungeons. When the Potions master found me in his office, I said I was under orders to search it."
-- Barty Crouch Jr, HP and the Goblet of Fire (emphasis mine)
As for what exactly would happen if you tried to Polyjuice into a dead person, I don't think there's any canon info. Maybe you'd wind up dead yourself, in that person's body. Maybe the potion would simply have no effect: it works via a magical link with the biology of another living person.
