Looks Like There's a Huge Polyjuice Potion Plot Hole in Harry Potter and Goblet of Fire
Barty Crouch Jr. seems to have a really strong plot armor.
In Harry Potter and the Goblet of Fire, we meet Professor Alastor Moody for the first time — only (spoiler alert, we guess?) it's not in fact him but rather Barty Crouch Jr, a death eater who used Polyjuice potion to pose himself as Moody to get Harry into the deadly Triwizard tournament.
Eventually "Moody" runs out of the Polyjuice potion and is revealed as Crouch Jr, but this happens after Voldemort returns. However, according to one fan theory posted on Reddit, it actually should have happened a long time before.
Barty lasted for one academic year without revealing himself, meaning that he had something like an infinite amount of Polyjuice potion to sustain him. The potion takes a month to make, but one dose only lasts an hour — which means Crouch Jr had to constantly have supplements with him. But just how much of that Polyjuice potion did he actually have stored?
"He needed enough to remain transformed for at least 8-9 hours a day, assuming he had nowhere to be before or after school hours. And as the story points out, he was actively stealing ingredients from Snape's storage room throughout the year, meaning he didn't have enough to last an entire year beforehand. How the hell did he pull this off?" the fan wondered.
For him to last an entire year, imagine how much potion he had to prepare. Some fans believe that it was hardly possible, even though a couple of people tried to explain how it could have worked.
"There doesn't seem to be a limit of how many 'doses' you can make at once. For example, Hermione made three doses of Polyjuice in the same one-month time frame that you would need to make one dose. In theory, with enough ingredients, BCJ could make 100 doses in the same, massive cauldron and it would still only take one month," Redditor SuiryuAzrael noted.
One person even did the math.
"Let's assume that he needs a shot glass sized dose, once an hour, 9 hours a day, 7 days a week. A shot glass is 44ml, that's 2.77L per week. That's not that much," Redditor ImmortalMagi revealed.
However, even if that explanation works, the entire plot twist with Crouch Jr being Moody still doesn't make sense story-wise, according to fans.
"The whole Barty Crouch Jr pretending to be Moody for an entire year is definitely the worst twist/ reveal of the whole series IMO It doesn't work in any practical way, plus it makes any future Moody interactions awkward considering the first year of his character being developed was [non-existent]," Reddit user Environmental_Tank_4 added.
Still, many people opt for omitting practical details and treating the Harry Potter saga like it should be treated — as a piece of fiction where one sometimes needs to forget about how things actually work in real life and enjoy the story.