Nagini seemed integral to Lord Voldemort's survival before he could be restored to his body, and we learnt, quite grotesquely, that Voldemort even tasked Wormtail to 'milk' Nagini so he could live off her venom to keep his strength up.
In “The Goblet of Fire,” Voldemort explains to Harry that he found “the essential ingredients for true rebirth” by drinking a potion of unicorn blood and Nagini's venom. She also sustains Voldemort with milk, which parallels breastfeeding.
In 1994, Death Eater Peter Pettigrew milked the venom from Nagini's fangs and used it, along with unicorn blood, to concoct a dark potion, which allowed Lord Voldemort's shattered soul to regain a rudimentary, but physical form.
Until then, Voldemort required the potion every few hours to keep his crippled body alive, and Pettigrew had to continuously milk Nagini for the venom to keep feeding his master.
Though it may later be revealed that the Dark Lord did indeed know that Nagini was a Maledictus, there's currently no indication that he (or anyone else) ever thought that she was anything other than a snake who was made into one of the Dark Lord's Horcruxes.
Nagini is loyal to Voldemort because he can speak with snakes. As a Maledictus, there probably isn't much time after the events in The Crimes of Grindelwald before Nagini falls to her blood curse, becoming a snake forever.
By 1994, Nagini was seemingly trapped in snake form and belonged to Lord Voldemort, with whom she had a special bond largely due to becoming a Horcrux after her master had killed Bertha Jorkins in 1994.
Harry can no longer speak it
Harry being an accidental Horcrux meant he was bound to Voldemort in so many ways, just like Voldemort was bound to serpents. Not only could Harry speak the language of the snake, but could see through the eyes of Nagini, another of Voldemort's Horcruxes, as it turned out.
Nonetheless, despite her initially benevolent nature, Nagini's blood curse eventually turned her into a snake permanently. Though it is unknown if she became evil as a result of that, or was turned evil as a result of Voldemort turning her into a Horcrux. As a snake, Nagini was completely loyal to Lord Voldemort.
There was a rumour that Nagini was the snake Harry released from the zoo in Harry Potter and the Philosopher's Stone. This was proven false, as Nagini is some type of viper while the snake in the zoo was a boa constrictor. Furthermore, the snake was given a male voice in the film, while Nagini is female.
Voldemort concludes that he is not yet the true master of the Elder Wand, because Snape killed its previous owner, and thus Voldemort must kill Snape to be the wand's master. Voldemort orders Nagini to kill Snape, and the great snake bites Snape's neck, mortally wounding him.
no! they were all busy killing the enemy's troops and so was Nagini. it takes a long time for a snake to digest the food it has swallowed.
Therefore, when Voldemort used the killing curse against Harry in Deathly Hallows - Part 1, he was actually killing part of his own soul, and Harry was able to survive. And after Neville killed Nagini, all Horcruxes were destroyed.
Dumbledore does not use any language to make one think that Nagini is anything more than a snake. But this could be despite his knowledge of Nagini's past because he has to factor his grand plans into everything he tells (or doesn't tell) Harry.
Bellatrix used a powerful "love potion" on Voldemort and they have sex while he is temporarily obsessed with her. She then uses obliviate on him while he sleeps (you know, he falls asleep after his post-sex cigarette) and tells everyone that the baby is her and her husband's.
The "most faithful servant" is Barty Crouch Jr., who has already been in place at Hogwarts working for Voldemort. The three dead include Evan Rosier, Wilkes, and Regulus Black.
When Harry and Hermione are on the first floor of Bathilda's house, Nagini (inside the corpse of Bathilda) tells Harry to "Come!" from the next room in Parseltongue. In reaction, Hermione jumps and clutches Harry's arm, and the two of them obey the command.
In short, no one knows exactly how Nagini ends up as Voldemort's closest ally. Evidently, something happened between the time of her joining Newt and the events of Harry Potter that pushed her to the dark side. She might even have met Voldemort while still human, and he was Tom Riddle.
Nagini, it turns out, was actually a Maledictus—a witch with a blood curse that turns her permanently into a beast (in her case, a giant snake). In the film, the witch is played by Claudia Kim.
It wasn't just inanimate objects that could become Horcruxes. Lord Voldemort's beloved snake companion, Nagini, was also transformed into one, and Dumbledore seemed to know it, ominously predicting that a day would come where Voldemort would 'fear for his snake'.
Rowling previously revealed that Nagini is a Maledictus, which means she carries a blood curse that will doom her to transform permanently into a beast. In a film extra called "Credence, Nagini and the Circus Arcanus," available on the "Crimes of Grindelwald" Blu-ray, Rowling said she "knew all along about Nagini."
Quirrell didn't use the Killing Curse on Harry, because Voldemort said “use the boy” to get the Sorcerer's stone from the Mirror of Erised. If Quirrell had killed Harry right away, he would have lost the chance to get the stone.
Deathly HallowsEdit
Nagini, Voldemort's snake, then eats Professor Burbage's dead body. A story about her "resignation" from Hogwarts appears in the Prophet, but members of the Order of the Phoenix discount it, as they are unable to locate her anywhere after that.
Nagini's Future After The Fantastic Beasts Movies
From that point on, she goes to the forests of Albania, presumably to live out the rest of her life as a gargantuan creature, perpetually bound in her scaly form.
Nagini seemed integral to Lord Voldemort's survival before he could be restored to his body, and we learnt, quite grotesquely, that Voldemort even tasked Wormtail to 'milk' Nagini so he could live off her venom to keep his strength up.