Sacrificial protection

Lily Potter is murdered by Lord Voldemort while standing in his way to Harry.

"It was love. You see, when dear, sweet Lily Potter gave her life for her only son, she provided the ultimate protection. I could not touch him. It was old magic. Something I should have foreseen."

— Voldemort on Lily Potter's sacrifice

Sacrificial protection is an ancient, powerful, and lasting magical protection that is created when one person sacrifices his or her own life willingly and out of love to save the life of one or more people.

Requirements and effects

Sacrificial protection can be conferred on a single person or on a group of people. In cases involving a single person, the protection prevents whoever murdered the person who sacrificed their life from physically touching the person saved, and will cause a Killing Curse cast at the saved person by the murderer to rebound. In cases involving multiple people, the extent of the protection is not known, but it seems that it is less than in single-person cases, so that spells cast by the murderer at those under the protection 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 person sacrificing him or herself actually dies since in the only known case in which sacrificial protection was conferred to a group of people, the intended victim survived.

In order for the protection to form, the sacrificing person 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 magical protection was conferred upon her son.

Harry Potter prepared to die by Voldemort's hand in order to protect his friends and allies.

Another effect of sacrificial protection binds the saved person to life when his or her blood is transfered to another person (perhaps this only works when the saved person's blood is transferred to the murderer) as long as that person lives. If the blood is transfered 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 Voldemort was able to touch Harry and harm him with spells after his resurrection.

Bond of blood

Dumbledore: "I put my trust, therefore, in your mother's blood. I delivered you to her sister, her only remaining relative."

Harry: "She doesn't love me. She doesn't give a damn —"

Dumbledore: "But she took you. 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."

— Albus Dumbledore to Harry Potter

Albus Dumbledore leaves infant Harry Potter and a note on the doorstep of 4 Privet Drive so that the bond of blood charm he placed on Harry can be sealed.

If the person who sacrificed their life was related to the person they saved, then a powerful charm can be cast upon the saved person to give them additional protection (although it is unknown how closely the two must be related for this charm to work). However, in order for this charm's power to take effect, another living blood-relative must first take the saved person into their home. Once activated, this bond of blood will prevent harm from coming to the saved person when they are in their relative's home, but it will break automatically when the saved person moves out permanently or turns seventeen (the age of majority in the British wizarding world), whichever happens first.

Known occurrences

• On the night of 31 October, 1981, Lily Potter sacrificed her life in order to protect her infant son, Harry, from Lord Voldemort. This placed Harry under magical protection, so that when Voldemort cast the Killing Curse at Harry in turn, the spell backfired, leaving Harry unharmed (save for a scar on his forehead) and Voldemort bodiless. Harry became the only known person to survive the Killing Curse because of the power of his mother's loving sacrifice. However, forseeing Voldemort's inevitable return, Albus Dumbledore furthered Harry's protection by casting the above-mentioned charm on him and leaving him in the care of his only living relative, Petunia Dursley, Lily's older sister.
• On 2 May, 1998, during the Battle of Hogwarts, Harry Potter willingly allowed himself to be hit with a Killing Curse cast by Lord Voldemort, so that the piece of Voldemort's soul residing inside him would be destroyed and the Dark Wizard could be defeated once and for all. This conferred a certain amount of protection on Harry's allies, making it so that spells Voldemort tried to place on them, including Silencing Charms and a Full Body-Bind Curse, quickly wore off.

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 offending witch or wizard can harm anyone protected by the sacrifice. 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, was able to do any damage to the Hogwarts army. However, the possibility of coincidence still remains.

Appearances

• Harry Potter and the Philosopher's Stone (First mentioned)
• Harry Potter and the Philosopher's Stone (film) (Appears in flashback(s))
• Harry Potter and the Chamber of Secrets (Mentioned only)
• Harry Potter and the Goblet of Fire (Mentioned only)
• Harry Potter and the Goblet of Fire (film) (Mentioned only)
• Harry Potter and the Order of the Phoenix (Mentioned only)
• Harry Potter and the Deathly Hallows (First appearance)
• Harry Potter and the Deathly Hallows: Part 2