Fidelius Charm

> "*An immensely complex spell involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret-Keeper, and is henceforth impossible to find — unless, of course, the Secret-Keeper chooses to divulge it. As long as the Secret-Keeper refused to speak, You-Know-Who could search the village where Lily and James were staying for years and never find them, not even if he had his nose pressed against their sitting room window!*"
> ― Filius Flitwick's description of the charm[source]
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The **Fidelius Charm** (*incantation unknown*) is an extremely difficult, multifaceted and potent charm that can be used to conceal a secret inside an individual's soul; the witch or wizard who houses the secret is known as the Secret Keeper. A dwelling whose location has been protected by this spell is then invisible, intangible, unplottable and soundproof. This is an extremely old spell, one of the most ancient of all.

## Nature

### Becoming Secret Keeper

When the charm is initially cast, one can choose more than one person to be Secret Keeper, though it is unknown if there is a limit as to how many people can carry the same secret in this way. Once the Secret Keeper dies, all the people who have learnt the secret from them will become the new Secret Keepers. If the Keeper has chosen not to reveal the secret to anyone (so that they are the only Keepers) then the secret rests with them forever.

It is unknown what criteria must be met before someone can qualify as a Secret Keeper. However, it *appears* that, to be eligible, one must be capable of divulging the secret if they wish to, as this would explain why wizards do not simply bestow the secret onto creatures who cannot speak a human language, or creatures such as house-elves, who can simply be ordered by their masters to not divulge the secret (as such an order would override their free will). It is also possible that the spell must be cast by the Secret Keeper him/herself, so only a wizard can be it.

### Revealing the secret

> "*Lily and James only made you Secret-Keeper because I suggested it... I thought it was the perfect plan... Voldemort would be sure to come after me, would never dream they'd use a weak, talentless thing like you... It must have been the finest moment of your miserable life, telling Voldemort you could hand him the Potters.*"
> ― Petter Pettigrew betrayed the Potter's secret[source]
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Once the secret has been implanted, the ***only*** method for another to learn it is for the primary Secret Keeper to divulge it to that person *directly*, it cannot be discovered any other way. Additionally, the disclosure must be completely voluntary, as methods of coercion such as Veritaserum, Legilimency, the Cruciatus Curse or the Imperius Curse have no effect on the charm.

The people to whom the Secret Keeper has already divulged the information (secondary Keepers) would not be able to pass it along even if they wanted to and the information in question cannot be learned even by stumbling across it, even if one were staring the secret in the face. For example, if someone were to hide a location in this way, even if a person were to stumble into the specific area they would not be able to recognise it for what it was (i.e. as the area they were looking for) and they would not therefore learn the location accidentally.

The method for the primary Keeper to voluntarily tell another person the secret can be verbal or written. It is also possible that primary Keepers can reveal information to another by *showing* it to them. This theory is postulated because whilst 12 Grimmauld Place was under this charm and being used as a base of operations for Harry, Hermione and Ron only after Dumbledore's death, the Death Eaters evidently became aware of 12 Grimmauld Place's approximate location knowing that Harry Potter had inherited the property from Sirius Black.

Despite watching the gap between numbers 11 and 13 when on the lookout for Harry, the house remained invisible to them until Yaxley grabbed onto Hermione Granger's arm while she, Harry, and Ron Weasley Disapparated away from the Ministry of Magic to 12 Grimmauld Place, where they had been hiding. It is explained that because Hermione (along with everyone else who knew the house's location) had been rendered Secret-Keeper by Dumbledore's death, she inadvertently took Yaxley past the protections of the Fidelius Charm. The trio subsequently abandoned the house as a hideout.

Once the secondary Keeper has received the information in either of these ways the information will still *appear* hidden to them until they start thinking about it, at which point the secret will reveal itself to them alone. For example, Alastor Moody gave Harry Potter a parchment with Albus Dumbledore instructing where the Order of the Phoenix's headquarters is. He then merely has to think about the said location whilst in the correct area and it would appear out of thin air, allowing him entry.

## Known Uses

 1995-1996
 Unknown
 Arthur used this charm on his households in 1998.

## Etymology

**"Fidelis"** is Latin, meaning trustworthy and faithful. **"Fidelius"** is the neuter comparative form of this word, meaning *more* trustworthy and *more* faithful. **"Fidelius"**can also translate to authors.