Bond of Blood

The Bond of Blood is an exceptionally powerful and ancient form of magic rooted in love and willing sacrifice. It is most famously associated with the protection that Lily Potter conferred upon her infant son, Harry Potter, when she sacrificed her own life to save him from Lord Voldemort. This act created a magical shield that not only caused the Killing Curse to rebound upon Voldemort but also formed the basis of a subsequent protective charm cast by Albus Dumbledore that kept Harry safe throughout his childhood. The mechanics of this bond were a cornerstone of the struggle between Harry and Voldemort.

• Type: Ancient Magic, Sacrificial Protection
• Invocation: The bond is created when a person willingly and knowingly sacrifices their life for another person whom they love, despite having the choice to save themselves.
• Effect: It provides the protected individual with a potent, lingering magical defense against their specific attacker. In Harry Potter's case, this protection initially manifested in two ways:
  1. It caused Lord Voldemort's fatal curse to rebound, destroying his physical body.
  2. It prevented Voldemort, in his spectral or resurrected forms, from being able to physically touch Harry without experiencing excruciating pain.
• Extension: The power of the original sacrifice can be reinforced through additional charms. Albus Dumbledore used the existing bond to create a powerful shield around the home of Harry's only living blood relative, his aunt Petunia Dursley.

Invocation by Lily Potter On 31 October 1981, Lord Voldemort arrived at the Potters' home in Godric's Hollow with the intent to kill Harry Potter. After murdering James Potter, Voldemort offered Lily Potter the chance to stand aside, as Severus Snape had requested he spare her. Lily refused and placed herself between Voldemort and her son, begging for Harry's life. By making this ultimate sacrifice when she could have chosen to live, she invoked this ancient magic, creating the Bond of Blood. When Voldemort then cast the Killing Curse at Harry, it rebounded, striking Voldemort instead and reducing him to a disembodied spirit. The Privet Drive Charm Following the attack, Albus Dumbledore devised a way to strengthen and prolong Lily's protection. He placed Harry in the care of his aunt, Petunia Dursley, Lily's sister. By accepting Harry into her home, Petunia, who shared Lily's blood, sealed a powerful charm Dumbledore had cast. This charm ensured that as long as Harry could call Number 4, Privet Drive his home, Voldemort could not touch or harm him there. This protection was conditional, requiring Harry to return to the Dursleys' home at least once a year. Voldemort's Miscalculation During his rebirth ceremony in the cemetery of Little Hangleton, Lord Voldemort sought to overcome the protection that prevented him from touching Harry. On the advice of Peter Pettigrew, he used Harry's blood as a key ingredient in the Regeneration Potion. Voldemort believed that by incorporating Harry's blood—and thus Lily's protection—into his own body, he would neutralize its power. While this did allow Voldemort to touch Harry without pain, it had a critical and unforeseen consequence. As Albus Dumbledore later explained, by taking Harry's blood, Voldemort inadvertently strengthened the Bond of Blood and tethered Harry to life. Lily's protection now existed within Voldemort's own veins, acting as a safeguard for Harry. As long as Voldemort lived, this connection ensured that Harry could not be permanently killed by him. When Voldemort struck Harry with the Killing Curse in the Forbidden Forest, the curse destroyed the part of Voldemort's soul residing in Harry (the accidental Horcrux), but Harry himself was able to survive and return to his body because of the tether created by the Bond of Blood.

The Bond of Blood's protection was not absolute and had specific limitations and conditions for its dissolution.

• The protection against physical touch was nullified after Voldemort took Harry's blood into his own body during his rebirth.
• The specific charm protecting Harry at Number 4, Privet Drive was destined to break under one of two conditions, whichever came first:
  1. When Harry Potter came of age at seventeen.
  2. If Harry no longer considered the Dursleys' house his home.
• Anticipating the charm's expiration on Harry's seventeenth birthday, the Order of the Phoenix arranged to move him to a safe location. This operation resulted in the Battle of the Seven Potters.

J.K. Rowling has stated that sacrificial love is “the most powerful magic of all” and that it is the “bedrock of the entire series.” The Bond of Blood is the ultimate manifestation of this theme, representing a power that the cynical and loveless Lord Voldemort could never understand or defeat. (J.K. Rowling interview)