Sacrificial protection

"Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. He didn't realise that love as powerful as your mother's for you leaves its own mark. Not a scar, no visible sign... to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever."

- Dumbledore regarding the power of love

Sacrificial protection is an ancient, powerful, and long-lasting counter-charm. This charm unlike others has no incantation and is endowed when one person (who we will call "the victim" for purposes of this article) ultimately sacrifices his or her own life willingly and out of deep and pure love to save the life of one or more people (to whom this article will refer as "beneficiaries").

When the person to make the sacrifice dies, the counter-charm is so powerful that the murderer can not physically touch the intended victim, as the protection lives on in their veins. Also, any spells cast on the beneficiaries wear off quickly.

Requirements
In order for the protection to form, the victim must be given the option to live, but consciously choose death. This is why James Potter's death did not confer magical protection on Lily and Harry in 1981; Voldemort was set upon killing James and thus never gave him an opportunity to choose to save himself. Lily, on the other hand, was offered the chance to step aside because Voldemort had promised Severus Snape that he would not kill her unless she got in his way. Her conscious refusal to comply with Voldemort's demand is why unusually strong magical protection was conferred upon her only son.

Effects
"But I knew too where Voldemort was weak. And so I made my decision. You would be protected by an ancient magic of which he knows, which he despises, and which he has always, therefore, underestimated — to his cost. I am speaking, of course, of the fact that your mother died to save you. She gave you a lingering protection he never expected, a protection that flows in your veins to this day."

- The effects of sacrificial protection

Sacrificial protection can be conferred on a single beneficiary or on a group of them. In cases involving a single person, the protection prevents whoever murdered the person who sacrificed their life from physically touching the person saved without experiencing excruciating pain, and will cause a Killing Curse cast at the saved person by the murderer to rebound. In cases involving multiple beneficiaries, the extent of the protection is not known, but it seems that it is less than in single-beneficiary cases, so that spells cast by the murderer at those beneficiaries will simply wear off more quickly rather than be reflected back (although it is unknown how that would apply to the Killing Curse). However, the difference in the level of protection could also be attributed to whether or not the victim actually dies since, in the only known case in which sacrificial protection was conferred to a group of people, the intended victim survived.

Another defensive effect of sacrificial protection binds the beneficiary to life when his or her blood is transferred to another person (perhaps this only works when the beneficiary's blood is transferred to the murderer) as long as that person lives. If the blood is transferred to the murderer, then the murderer will be able to overcome some aspects of the protection. Evidence of this can be seen in the way that Lord Voldemort was able to touch Harry Potter and harm him after his rebirth and resurrection.

Bond of blood
"She may have taken you grudgingly, furiously, unwillingly, bitterly, yet still she took you, and in doing so, she sealed the charm I placed upon you. Your mother's sacrifice made the bond of blood the strongest shield I could give you."

- Explanation of the bond of blood



If the victim was related to the beneficiary, then a powerful charm known as the bond of blood can be cast upon the beneficiary to give them additional protection (although it is unknown how closely the two must be related for this charm to work). This charm prevents any harm from coming to the beneficiary from the murderer while they are in a blood-related relative's home.

However, in order for this charm's power to take effect, the living blood-relative must first take the saved person into their home willingly. Once activated, this bond of blood will prevent harm from coming to the beneficiary when they are in their relative's home but it will break automatically when the saved person moves out permanently or turns seventeen (the in the British wizarding world), whichever happens first.

Behind the scenes

 * It would seem that the protection can take effect even if the opportunity for self-preservation is presented only by circumstance. In 1998, during the Battle of Hogwarts, Voldemort gave Harry one hour to surrender himself, vowing to hunt him down if he did not show up in that time. Nonetheless, although Voldemort was determined to kill Harry, Harry's sacrificial protection worked to save his friends, presumably because he willingly gave himself up despite having enough time to try to run away, whereas James Potter was only given a minute's notice of Voldemort's arrival. Also, he arrived to face Voldemort just after the required hour and by that time Voldemort thought he wasn't coming.
 * It is unknown if anyone employed by the murderer can harm a beneficiary. This is seemingly evidenced during the Battle of Hogwarts, where it is believed that Harry protected his friends from Voldemort, after which, not even any Death Eaters, much less Voldemort himself, were able to do any damage to the Hogwarts army.
 * Because of Harry's sacrificial protection, the spells that Voldemort and his Death Eaters cast did not work properly. Voldemort's Silencing Charm did not keep the Hogwarts residents quiet for long, and Neville Longbottom was able to break the Full Body-Bind Curse Voldemort cast on him. Yet also in the final film, Voldemort casts the Stunning Spell on Neville out of anger after seeing Harry alive. This spell did not hold, either, as Neville woke up soon after. Furthermore, neither Voldemort or the Death Eaters were able to do any damage to the Hogwarts students, Professors, Hogsmeade villagers, Order of the Phoenix or other participants. Interestingly, Harry is also seen in the films as being able to deflect Killing-Curses with a Shield-Charm, although this may be to do with the allegiance of the Elder Wand rather than the sacrificial protection. This is the sole place in the final film where the blocking of a Killing-Curse can be considered to be theoretically possible, as other blocks (such as by Bellatrix) exist to elongate duels and increase drama.
 * It is seen during the Battle of Hogwarts that the spell only protects living people, as the Dark Wizards were still able to destroy areas of Hogwarts.
 * Lord Voldemort's inability to understand the power of love made him severely underestimate and misunderstand the power of this protection. He believed that by taking Harry's blood for his regeneration, he would be able to bypass the shielding, and thought being able to touch Harry, was evidence of such; contrarily, this strengthened the protection by preventing Voldemort from killing Harry.
 * Interestingly, the only two occurrences of the counter-charm have been through the Potter family in terms of Lily Potter (nee' Evans) and Harry Potter, mother and son. It is yet to be shown that this charm is demonstrated by someone outside the Potter family.

Appearances

 * PS undefined
 * PS F

Notes and references
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