We all know about the Fidelius Charm. It can be used to hide houses and locations from view. A number of fanfic authors have asked the question of how come James Potter couldn't be the Secret-Keeper, as a sort of "duh, stupid" remark on the magic. (Though I'd argue he wasn't because he couldn't be: that a Secret-Keeper has to avoid the location of the Secret, or else the magic doesn't work. Short visits are fine, as seen by Dumbledore and Grimmauld Place, but you can't live there.)

However, here's the actual description from the books:

Note that the description of the charm does not mention that the secret of a location is hidden inside a soul. Just a secret. A fact.

So that got me wondering: what else could the Fidelius Charm be used for? Could Voldemort have used it to hide knowledge of how he used to be Tom Riddle? Have there been certain magical secrets, such as how to make certain objects or cast some spells, that have been lost to time? Is making a location Unplottable related to the charm, or separate?

Has anyone come across stories that play with this concept, or discussions about it?

 

Prince of Slytherin

 

I should have come across this thread earlier: I wrote my thoughts up in the personal headcanon thread wrt the Fidelius. Maybe that aligns with what you might want to discuss?

 

I don't think it can erase knowledge, it merely hides a secret location.

Voldemort could have hidden his Horcruxes with it but chose not to.

Perhaps you can only keep one secret at any given time.

 

He'd have to trust the secret that he created Horxruxes to at least person at the time, basically for all eternity. I doubt that was ever an acceptable risk for him.

 

Other uses that I can think of is that you could use it to hide a secret basement in your house. Your house and it's public areas would be accessible to anybody but the Secret Basement would only be known to you.

 

I'm completely in agreement with Sesc on this, I prefer when the strength/success of the protection is derived from how well known the secret is when the spell is cast.

I'd also say that using it on anything other than a physical location is...pretty boring. When you take it to the level that Prince of Slytherin takes it it becomes ridiculously OP and it basically a "how to win at life" spell.

 

I mean Voldemmort in Prince of Slytherin kinda cheated by

Spoiler: Spoiler for POS

turning his Horcrux into the secret keeper, thereby forgoing the need to trust another person

.

In most situation you can create real conflict based on how much the secret keeper is trusted.

 

Note that in Deadly Hallows Bill was able to divulge to Ron and Harry that Arthur was secret keeper of Muriel's house and that they are hiding there.

It is so, because Bill was aware of it before the charm was actually cast and secret became concealed in the living soul.

The location isn't concealed from the view but rather a secret. Flitwick said, "not even if he had his nose pressed against their sitting room window!" The existance of property is quite poor secret, but the inhabitants of it, if they arrived in secret and recently, known to only a couple of people, are not the widespread knowledge and therefore it makes for a good secret.

Bathilda was able to visit Potters - she probably knew they were there, and was friendly with them.

Edit: I just noticed the title and realised I haven't answered it. It is a charm with singular use - hiding a secret. If it is ineed a secret, the charm will help with keeping it so, and if it is widely known, it would do very little. I suppose you could be creative about the definition of secret, but that's all there is to this charm.

 

When Dumbledore died, everyone who knew the secret of Grimmauld Place was able to let others in.

So I'd tend to view it as a forced secret, and probably limited to actually secret information. You couldn't cast a fidelius on what day comes after Wednesday, because that's common knowledge. You could cast a fidelius to hide your location.

But I also like my magic to be a bit whimsical, and feel more than just foolish wand-waving.

So it's the act of imparting the secret that gives it power. If it's something you tell someone without care, then it's not going to be much use. But if you tell your closest friend a secret that is protecting your life, something that will literally kill you if it leaks, then the spell is much more powerful - Voldemort can be looking right at you, but not see you.

I've previously put some thoughts on the fidelius in this thread here, which a few others did too.

 

JKR's writing from 2015:

"The Fidelius Charm is extremely ancient and still used to this day. It involves the concealment of information inside a living person. The chosen person, or Secret Keeper, is the only person who is thenceforth capable of revealing the protected information to others, however many previously knew it. If the Secret Keeper shares the hidden information, the person to whom he or she has confided it will be bound by the Fidelius Charm and find it impossible to pass the information on."

As for fanfics that put good spins on it, there's Not by Force by the divine comedian, which makes Sirius secret keeper and Pettigrew still the traitor. It's a short dystopian fic where Sirius is captured and tortured for the information, which he can't give 'by force', so they have to figure out other ways of getting the information from him.

The Renascentia series has Grimmauld Place as the headquarters of the Order, although plenty of members of the Black family can still both see and visit it because the building itself and its status as ancestral home is not under the fidelius. It has Regulus and Andromeda Black wandering around the house unable to see the Order members who are also there.