Patronus Charm

The Patronus Charm (Expecto Patronum) is the most famous and one of the most powerful defensive charms known to wizardkind.[4] It is an immensely complicated and extremely difficult spell that evokes a partially-tangible positive energy force known as a Patronus (pl. Patronuses) or spirit guardian.[3] It is the primary protection against Dementors and Lethifolds, against which there are no other defence.

There are two types of Patronuses. Corporeal which means a Patronus with a particular shape and form and uncorporeal Patronus. Uncorporeal Patronuses have no particular shape and do not protect against dementors the way corporeal Patronuses do. However, some wizards like Remus Lupin choose to cast uncorporeal Patronuses to hide their identity.

History
It is evident from old woodcuts and scrolls that the Patronus Charm has been used since ancient times.[6] Therefore, it is unknown who created it, or when it was first invented. The charm also has a long association with those fighting for lofty or noble causes (those able to produce corporeal Patronuses were often elected to high office within the Wizengamot and Ministry of Magic).[4]

According to legend one of the most famous Patronuses of all time was a lowly mouse, which belonged to a young wizard called Illyius.[7] Illyius cast the Patronus Charm when his village was being attacked by the Dark wizard Raczidian and his army of Dementors. Despite the mouses diminutive size, it shone with a brilliant light, bringing the Dementors to a halt as it nimbly moved through the ranks of fleeing villagers.[8] Enraged, Raczidian decided to enter the fray himself, and tried to summon a Patronus to ward off Illyius's mouse. However, he failed to remember that only the pure of heart can produce a Patronus, and thus for the first time in history, it was revealed what happens when a competent, but unworthy wizard or witch attempts the spell. Maggots shot out of Raczidian's wand and quickly devoured him as they engulfed his entire body. The villagers hailed Illyius as a hero.[8]

Harry Potter took anti-dementor lessons in order to learn the advanced charm and so was one of the youngest to attempt this charm with actual results. During a Quidditch match against Ravenclaw in 1994 he cast his very first corporeal Patronus and again in June when he along with Hermione Granger and Sirius Black were being attacked by over a hundred Dementors, he cast a corporeal Patronus powerful enough to drive them all away.

Alfie Campbell knew this spell at the same time as Harry Potter [9], but it is unknown how.

In 1995, Harry cast the charm against a boggart that he thought was a dementor during the third task of the Triwizard Tournament. The following summer he came under attack by two Dementors and managed to drive them away with the charm, leading to him being put on trial for underage magic in an attempt to discredit him.

Harry also taught the members of Dumbledore's Army the charm and some were even successful in casting it.

The charm was used frequently to ward off dementors such as when the five escaped from the Ministry of Magic after obtaining the Horcrux locket and during the Battle of Hogwarts. Severus Snape also conjured a Patronus to guide Harry to the hiding place of the Sword of Gryffindor.

The Order of the Phoenix would send out messages with their Patronuses such as Kingsley Shacklebolt and Arthur Weasley who in 1997 delivered warnings.

Nature
The Patronus represents that which is hidden, unknown but necessary within the personality.[10] When a human confronted with inhuman evil, such as the Dementor, must draw upon resources he or she may never have needed, and the Patronus is the awakened secret self that lies dormant until needed, but which must now be brought to light.[11] Patronuses take forms that their casters might not expect, for which they have never felt a particular affinity, or (in rare cases) even recognise.[12] Every Patronus is as unique as its creator and even identical twins have been known to produce very different Patronuses.[13]

The unusual witches and wizards who produce a Patronus that takes the form of their favourite animal is an indicator of obsession or eccentricity.[14] Here is a wizard who may not be able to hide their essential self in common life, who may, indeed, parade tendencies that others might prefer to conceal.[15]Whatever the form of their Patronus, you would be well-advised to show respect, and occasionally caution, towards a witch or wizard who produces the Patronus of their choice.[16]

Casting
The vast majority of witches and wizards are unable to produce any form of Patronus, and to create even an intangible one is generally considered a mark of superior magical ability.[4]

Given their long affinity with humans it is perhaps unsurprising that among the most common Patronuses when cast (although it must be remembered that any corporeal Patronus is highly unusual) are dogs, cats, and horses.[17]

To successfully cast the spell, one must muster the happiest memory they can think of (the happier the memory, the better the charm will work)[1] and begin drawing circles with their wand so as to increase the power of their spell.[6] They must then say the incantation, Expecto Patronum; the Patronus will come from the tip of the wand and can be directed towards a target by pointing one's wand at said target.[18] It is possible to disguise the form one's Patronus takes, which was done both by Severus Snape to hide his love for Lily Evans, and by Remus Lupin, who felt it would give away his condition.[4]

Also some witches and wizards may be unable to produce a Patronus at all until they have undergone some kind of psychic shock.[19]

Difficulty
The Patronus Charm is widely regarded as advanced magic, far beyond N.E.W.T.-level; in 1994 Remus Lupin stated that the charm was, in fact "ridiculously advanced".[1]This charm was, indeed, so perilous, few wizards/witches, could conjure up a true Patronus. It is very complex and many qualified wizards and witches have trouble with it.[4] In fact, Harry Potter is one of the youngest known wizards able to cast a Patronus; he was taught how to do so in early 1994 at the age of thirteen by Remus Lupin.[20] In a Dumbledore's Army lesson, Harry taught the members how to use the charm. Some were even successful in casting a corporeal form, though Harry said this might be because there was no Dementor to make them frightened.[21] However, six members were later able to cast corporeal Patronuses in the presence of Dementors.[22] Being able to cast a patronus, whilst fighting Dementors or not, is not required to graduate from Hogwarts so it is something that is taught under special circumstances.

Amelia Bones and potential members of the D.A. were all very impressed when Harry Potter and Alfie Campbell revealed that they could cast not only a Patronus Charm but a corporeal one to boot, which is notably more difficult than casting an incorporeal one. Given that the success of the charm is directly reliant on the caster retaining a particular mental state the Charm is more difficult to cast in emotionally trying circumstances. For instance, Harry Potter, Ron Weasley, Hermione Granger, Alfie Campbell and Sam Ainsley all had difficulty casting their Patronuses when under the negative influence of Salazar Slytherin's Locket, one of Lord Voldemort's Horcruxes, and after witnessing the death of Fred Weasley in the final battle.[22] This feature of the Charm is particularly unfortunate since the Charm's primary use is to defend against Dementors, Dark creatures specifically equipped to mentally unhinge people (and hence is partly why it is regarded as such advanced, difficult magic).

Self-confidence may also play an important role in casting the spell. In 1994 Harry and Sayef are able to cast the spell successfully, driving off a large number of Dementors (which according to Severus Snape is only achievable by a very powerful wizard) thus saving Sirius and a younger version of Harry, seemingly without recalling a happy memory, when he realises that he has already done it. Although Harry could have had a 'happy memory' upon realising that he had saved all four of their souls.

Worthiness
It is a general belief held by the wizarding world that only those who are pure of heart are able to cast Patronuses; this, however, is untrue, as several characters with negative personality traits are able to cast a fully-fledged Patronus.[4]Although generally Dark witches and wizards will not try to produce a Patronus, not having any need for one, most Dark wizards will be devoured by maggots coming from their wand and consuming the caster.[6]

For this reason, Lord Voldemort and his Death Eaters were not able to cast a Patronus Charm (not that it was necessary, as they already had the dark creatures under their control via their affinity to darkness, and would have no use for Patronuses).[23] However, some witches and wizards of questionable morals, such as Dolores Umbridge, are able to produce corporeal Patronuses, Umbridge doing so despite the fact that she was considered an evil person; her wearing of Salazar Slytherin's Locket, which was one of Voldemort's Horcruxes, was what enhanced her strength due to her evil affinity.[4] She was able to produce a corporeal Patronus due to the enhanced strength. Conversely, Draco Malfoy was unable to cast one despite his waning evil. Severus Snape is the only Death Eater capable of casting the charm, as his love for Lily Evans was his one redeeming point.

The Patronus
A successfully conjured Patronus can take two forms: non-corporeal or corporeal, and both types vary greatly in their appearances and strength.

Incorporeal
An incorporeal[24]Patronus is one which does not resemble any living creature and has few distinguishing features (if any). Incorporeal Patronuses resemble a burst of vapour or smoke without any clearly defined form shooting from the tip of the wand. While they may be partially effective at halting dementors (but not repelling them) and shielding the caster from them, incorporeal Patronuses are not "fully-fledged" Patronuses, and are regarded as a more primitive or weaker version of the true Charm.

Corporeal
A corporeal Patronus is one that is fully-formed, taking the shape of a bright-white, transluscent animal. The specific animal forms that corporeal Patronuses take vary from person to person and reflect each other's personality.

Patronus forms, however, are subject to change if the caster goes through an emotional upheaval of some sort, including falling in eternal, unchanging love.[25] For example, Nymphadora Tonks's Patronus changed from its previous form to that of a four-legged creature which others guessed was a werewolf because then it would reflect her love of Remus Lupin, himself a werewolf.[21] Another example is Severus Snape, whose Patronus was that of a doe, the same as Lily Evans, though this may have been the case all along rather than a change from its original form, as Snape was in love with Lily for most of his life.

Based on the fact that Patronuses are conjured by recalling happy memories, it stands to reason that a Patronus might change its form after one falls in love and the memories used to conjure the Patronus largely revolve around the person the caster is in love with. In addition, it seems that some couples have "complementary" Patronuses (male and female forms of the same animal), such as Lily and James Potter. It is, however, unknown if this is a coincidence or not. If a wizard is an Animagus and can summon a corporeal Patronus, the two may take the same form, as was the case for Minerva McGonagall, James Potter, Alfie Campbell and Sam Ainsley.[22]Remus Lupin's Patronus takes the form of a wolf, rather than a werewolf; whether or not all werewolves would generate a similar Patronus is unknown.

Most Patronuses take the form of an ordinary animal. Magical creatures, such as Albus Dumbledore's phoenix Patronus, are uncommon. It is extremely rare for Patronuses to take the form of extinct animals.[6] Hedley Fleetwood's woolly mammoth Patronus is a notable exception.[6] Andros the Invincible was the only wizard capable of casting a Patronus the size of a Giant, although whether it was a giant or not is unknown.

The corporeal Patronus is also better at repelling Dementors than the non-corporeal form.

Uses
There are two known uses for the Patronus Charm. The first and main use of the Patronus is to drive off certain Dark creatures such as Dementors and Lethifolds, and is the only known charm that will work against them. As Dementors feed on happy memories to render humans to drown in sorrow and sadness, the Patronus acts as a shield of sorts, of which the Dementor would try to feed off instead — the Patronus is comprised exclusively of positive feelings and cannot comprehend negative emotion, so the Dementor's influence cannot harm it.

The other use was devised by Albus Dumbledore, who invented a way of using the Patronus (corporeal and non) as a means of communication. They can deliver messages, speaking with the voice of the caster. This source of communication is believed to be exclusive to the members of the Order of the Phoenix. Using the Patronus for communication offers great advantages in security, as Patronuses identify the caster and are Dark Arts-proof.[21] A good example of this was when Minerva McGonagall used her feline Patronus to call for help to the other heads of houses in 1998 when she found out Harry Potter had returned to Hogwarts in search of Rowena Ravenclaw's Diadem. Multiple Patronuses can be cast for communication, as McGonagall was able to create three. Another is when Severus Snape used his Patronus to lead Harry Potter to a pool in the Forest of Dean in 1997, where he had laid Godric Gryffindor's Sword for Harry to retrieve. It is unknown if Snape had conjured the Patronus with instructions or if he was hiding and controlling it for this task. Harry's was able to follow both oral and physical commands. They also only remain active whilst the caster is focusing on them. If they are not protecting anyone, Patronuses seem to take on the traits of the creature they resemble and generally follow their caster around. This makes it unsure whether or not they are sentient.