======Bond of Blood Charm======
=====Magical Properties=====
  * **Type:** [[Ancient Magic]], Sacrificial [[Protection]], [[Charm]]
  * **Creator:** The specific application for [[Harry Potter]] was initiated by [[Lily Potter]]'s sacrifice and subsequently extended and sealed by [[Albus Dumbledore]].
  * **Basis:** An act of willing, loving self-sacrifice by one person to save another. This is a form of deep magic that does not require an [[incantation]] or [[wand]] work.
  * **Effect:** Creates a powerful, lingering magical protection over the saved individual. When anchored to a home shared with a blood relative of the sacrificed person (in this case, [[Lily Potter]]'s blood living on in her sister, [[Petunia Dursley]]), it prevents the target's primary enemy from touching or harming them while they are within the confines of that home. The charm is fueled by love.
  * **Duration:** The protection placed on [[Harry Potter]] at [[Number Four, Privet Drive]] was designed to last until he came of age at seventeen, or until he no longer considered the location his home, whichever came first.
=====History and Known Uses=====
The only known instance of this specific charm was the one used to protect [[Harry Potter]]. Its existence began on 31 October 1981, when [[Lily Potter]] sacrificed her own life to shield her infant son from [[Lord Voldemort]] in their home at [[Godric's Hollow]]. This act of sacrificial protection was so powerful that it caused [[Lord Voldemort]]'s killing curse to rebound, destroying his physical body and leaving [[Harry]] with only a lightning-bolt scar. The initial effect of this magic was that [[Voldemort]], in his spectral form, could not physically touch [[Harry]]. This was demonstrated when [[Professor Quirrell]], who was sharing his body with [[Voldemort]], was burned to ash upon making contact with [[Harry]] in the chambers beneath [[Hogwarts]].
Recognising the power of this ancient magic, [[Albus Dumbledore]] sought to strengthen and prolong it. He did this by placing [[Harry]] in the care of his only living blood relative, his aunt [[Petunia Dursley]]. By Petunia accepting [[Harry]] into her home, she sealed the powerful blood protection. As [[Dumbledore]] later explained, as long as [[Harry]] could call the place where his mother's blood dwelled "home," [[Voldemort]] could not harm him there. This is why [[Harry]] had to return to the [[Dursleys]] on [[Privet Drive]] every summer, despite their mutual animosity.
In 1995, [[Voldemort]] attempted to circumvent this protection. During his rebirthing ceremony in the [[Little Hangleton]] graveyard, he used [[Harry]]'s blood, believing that by sharing the blood protection, he would be able to touch [[Harry]] without harm. While this did allow him to bypass the prohibition on physical contact, [[Dumbledore]] later revealed that [[Voldemort]] had made a grave error. By taking [[Lily]]'s protection into his own veins, he tethered [[Harry]] to life, ensuring [[Harry]] could not be killed by him so long as [[Voldemort]] himself lived.
The charm's power over the [[Dursleys]]' home was absolute. When [[Vernon Dursley]] attempted to throw [[Harry]] out of the house in the summer of 1995, [[Dumbledore]] sent a [[Howler]] to [[Petunia]] with the message, //"Remember my last,"// a reminder of the agreement she made to take [[Harry]] in and the protection it afforded him.
The charm finally broke, as predicted, on [[Harry]]'s seventeenth birthday, 31 July 1997. In anticipation of this, the [[Order of the Phoenix]] enacted a plan to move [[Harry]] from [[Privet Drive]] to a safe house a few days before his birthday, an operation that resulted in the [[Battle of the Seven Potters]].
=====Nature and Limitations=====
The Bond of Blood Charm is not a spell that can be learned or cast in a conventional manner. It is a manifestation of ancient magic that arises from a specific, profound act: pure, loving self-sacrifice. It is considered one of the most powerful forms of magical protection known.
The primary limitation of the charm, as applied by [[Dumbledore]], was its specific conditions:
  * **Location-Based:** The full protection was only active while [[Harry Potter]] was at his home at [[Number Four, Privet Drive]]. While the base protection from [[Lily Potter]]'s sacrifice always lingered in his blood, the impenetrable shield against [[Voldemort]] was tied to this location.
  * **Duration:** The charm was temporary and set to expire when [[Harry]] reached the age of magical maturity (seventeen).
  * **Voluntary Anchor:** The charm required [[Petunia Dursley]]'s acceptance—however reluctant—of [[Harry]] into her home to be sealed. If she had refused him at the outset, or successfully thrown him out later, the charm would have broken.
There is no known counter-spell for this type of magic. [[Lord Voldemort]]'s only recourse was to wait for the charm's conditions to expire, as he and his [[Death Eaters]] could not force their way into the [[Dursleys]]' home to attack [[Harry]].
=====Behind the Scenes=====
In interviews, J.K. Rowling has explained that the concept of a mother's sacrificial love being the most powerful magic is a central theme of the series. This ancient magic is what [[Voldemort]], with his inability to understand love, consistently underestimates and fails to comprehend, which is ultimately a key to his downfall.
In the film adaptations, while [[Professor Quirrell]] is still shown to be burned by [[Harry]]'s touch in //Harry Potter and the Philosopher's Stone//, the detailed explanation of how [[Dumbledore]] extended this protection by tying it to the [[Dursleys]]' home is significantly reduced. The crucial conversation between [[Harry]] and [[Dumbledore]] at the end of //Harry Potter and the Order of the Phoenix//, where the charm is fully explained, is largely omitted from the film (film).