The 'Harry Potter' book and film series continue to intrigue fans all over the internet as new theories pop up on social media on a regular basis. One of the most recent fan theories involved a change in the history of the House of Slytherin, where Cassius Warrington is chosen as a champion in 'Goblet of Fire' instead of Cedric Diggory.

There is another 'Harry Potter' fan theory that is currently making its rounds online, and it may prove to be the darkest and bloodiest theory in the fandom. According to The Huffington Post, Reddit user jodatoufin wrote about the connection between the Killing Curse 'Avada Kedavra' and 'Abra Cadabra' and the conflict between muggles and wizards.

"I don't think the naming of Avadra Kedavra is by mistake. While I'm not sure on the entomology of the words itself (though Kedavra seems very similar to the word cadaver, which is fitting) I'm pretty sure it's intentionally similar to the famous magic words 'Abra Kadabra,'" the Redditor wrote.

"What I think we're supposed to take away from that is that, in the times before the statute of secrecy, the interactions between muggles and wizards were often violent and deadly. So much so that, even after the idea of wizards faded into mythology, among muggles the killing curse became a thing of folklore," jodatoufin continues. "Granted, over time the pronunciation became bastardized from 'Avada Kedavra' to 'Abra Kadabra,' but I think it's one of the few things that stuck among muggle culture since the statute of secrecy."

The 'magic words' theory got even darker when another Redditor commented on how the invention of a deadly weapon ruined the peace between muggles and wizards.

"IMO, wizards and muggles coexisted for most of history, but relations became strained circa the invention of guns," mindbleach wrote, mentioning that any battles between the two could easily be won by muggles with their new weapons. "The words 'abra kadabra' come to us as artifacts of the final battles - reappropriating and mocking the enemy."

It sure sounds like 'Abra Cadabra' isn't as harmless as a spell to pull a rabbit out of a hat after all.