Voldemort had a special relationship with Nagini, as she was his pet and one of his Horcruxes. According to Dumbledore, Voldemort had strong feelings for Nagini that he had not for anyone else; she was the one living thing that he had ever cared about.
Lord Voldemort and Nagini had a special relationship
As a Parselmouth, (i.e. able to talk to snakes) Voldemort could communicate with her, and the pair often sent each other messages, even suggesting a telepathic connection at times.
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.
In Harry Potter, Nagini is one of Voldemort's closest followers, if not the closest. He turns her into a Horcrux, which attests to how close they are. Dumbledore eventually refers to Voldemort as being as fond of Nagini "as he could be of anything." However, the story of how they met is difficult to piece together.
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.
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.
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.
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.
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'.
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.
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.
She was dieting and didn't want greasy food.
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.
The only "emotion" Voldemort felt when Nagini died was fear because she was the second to last piece of his soul. If Nagini wasn't a horcrux, he wouldn't even have kept her around. When Voldemort said “I regret it” after killing Snape, what was he feeling?
In the movies, Nagini was the one who killed Snape in the boathouse. The Maledictus meets her end when Neville Longbottom finds Gryffindor's sword and, in an attempt to destroy the final Horcrux, cuts off her head.
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.
Harry Potter and the Deathly Hallows
In this book, Rowling reveals that Bellatrix is the guardian of Helga Hufflepuff's cup (though she is unaware that it is a Horcrux), which Voldemort has entrusted the Lestranges to keep in their Gringotts vault.
Harry is never in a position to 'chat' to start with. She's there in the graveyard but Harry is surrounded by Death Eaters and Voldemort, he can't sneakily talk to her.
Voldemort, weakened by his long stint as "less than the meanest ghost' 69 insists on making one more Horcrux. And unlike with Harry, Voldemort did say the spell when he killed Bertha Jorkins to make Nagini a Horcrux.
J.K. Rowling recently gave more insight into one of the most controversial characters in the Wizarding World: Nagini, who was known only as Voldemort's snake in "Harry Potter," but appears as a woman in the prequel series, "Fantastic Beasts."
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.
Because Nagini also happens to be the name of another iconic “Harry Potter” character — Lord Voldemort's magical, extremely murderous pet snake. Well, just in case there was any doubt, “Harry Potter” creator JK Rowling confirmed the two characters are one and the same.
Once he learned that his horcruxes were being hunted, he knew Nagini was at risk. He couldn't know how his enemies had been able to find his other horcruxes, but he had to suspect at the least the possibility that it was by some magical means unknown to him, perhaps devised by Dumbledore.
Also, when Neville killed Nagini in Harry Potter and the Deathly Hallows Part 2, she disintegrated in the same way that Voldemort did. Nagini was the last Horcrux to be destroyed, and Voldemort was weaker each time one was destroyed.
After Voldemort was gone, Nagini decided to follow her dreams. She went to Brazil to join other snakes in the Amazon rain forest. While there, her adventures with Voldemort inspired her to write a song in Parseltongue called "I Thought You Were Pretty Cool But Then You Couldn't Even Defeat a Baby.