As Tom Riddle discovered his muggle inheritance, his hatred towards both his family and magical society increased, leading him to the path of evil and to adopt the moniker Lord Voldemort.
It was around this time that Riddle gave himself the alias 'Lord Voldemort', to spare himself of the reminder of his 'filthy Muggle father', who he later learned had abandoned his wife after learning she was a witch (although in reality he left her after she stopped controlling him with a love potion).
Harry Potter: Voldemort Was Evil Because of His Mother's Twisted Mistake. A problematic series of decisions from Voldemort's mother decades before the events of Harry Potter might explain why Voldemort became evil.
Voldemort's obsession with blood purity signifies his aim to rid the wizarding world of Muggle (non-magical) heritage and to conquer both worlds, Muggle and wizarding, to achieve pure-blood dominance.
Voldemort wanted to kill Harry because he believed in a prophecy that stated Harry would be the one to defeat him. The prophecy also mentioned that the chosen one would be born to parents who defied Voldemort three times, which applied to both the Potters and the Longbottoms.
The REAL Reason Voldemort Became EVIL - Harry Potter Theory
Why can't Voldemort touch Harry?
Quirrel couldn't put his hands on Harry without getting burned because he was sharing his body and soul with the spirit of Lord Voldemort at the time, and Lily Potter's death invoked a powerful blood-magic that prevents Voldemort from causing Harry any harm.
Voldemort made some crucial choices upon hearing the prophecy, and these choices were his own undoing. Voldemort's own narcissism caused him to choose Harry as he was half-blood like Voldemort, and this meant he viewed him as his equal. Also, Voldemort's first choice to follow the prophecy was the cause of his undoing.
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
In the battle that ensued, the prophecy was destroyed, and Lucius and his comrades were imprisoned in Azkaban in 1996. Although Voldemort broke them out of prison in 1997, he was displeased with Lucius for his failures and treated the Malfoys with much disdain and abuse.
Notably, Voldemort appeared to be entirely unaware of this split, as he later created a seventh Horcrux in his quest to have six, and continued to target Harry Potter despite him now holding part of Voldemort's own soul.
Dolores Umbridge is. She's among some of the nastiest characters in the whole series (along with Fenrir Greyback (ew)). In some ways, she was definitely more sinister than Voldemort.
By Harry Potter and the Deathly Hallows, it's a stretch to call Draco a villain anymore. We just watched — or read — him struggle to reconcile his choices and morals in The Half-Blood Prince. He can no longer justify his actions, and is far more aware of the evil he was born and raised into.
The prevailing theory has been that Voldemort gradually lost his nose (and humanity) throughout his life due to his exclusive use of Dark Magic. The more Dark Magic he tapped into, the less human he became both figuratively and literally. This was only amplified as he split his soul to create the Horcruxes.
Pettigrew mixed up a potion for Voldemort using unicorn blood and the venom of Nagini. With this potion, they were able to create a new body for Lord Voldemort to finally return to. However, this body was not what Voldemort needed to return to his fearful leadership form. Instead, it was that of a scaly, hairless baby.
As revealed during his confrontation with Dumbledore, Draco was an insecure boy incapable of committing cold-blooded murder and was forced to do Voldemort's bidding under the threat of his and his parents' deaths.
In his memoir, Felton said that Fiennes improvised Voldemort awkwardly hugging Draco Malfoy. "It gave me goosebumps then, and the memory gives me goosebumps now," Felton wrote.
She married Rodolphus Lestrange after leaving Hogwarts "because it was expected of her" to marry a pure-blood. However, Rowling stated in an interview that Bellatrix truly loved Voldemort.
Snape's strained relationship with Lily, who chose James and allowed him and his clique to bully Snape, further pushed him towards the Death Eaters. Despite his love for Lily, the pain from his adolescence couldn't erase the trauma. Snape's redemption came when Lily was murdered by Voldemort.
Although he wasn't turned into a werewolf, he did develop some wolfish tendencies such as a liking for very rare steaks. He married Fleur on 1 August 1997, although their wedding was disrupted by the arrival of Death Eaters following the fall of the Ministry of Magic.
Severus Snape's nickname, the Half-Blood Prince, was a clever description of his half-blood lineage. Snape chose the name as a tribute to his mother and to distance himself from his muggle father, drawing an interesting parallel between this character and Lord Voldemort.
In Harry Potter and the Deathly Hallows Part 2, Neville is actually the person who destroys Voldemort's last Horcrux in Nagini, rendering him mortal, meaning that he and Harry truly delivered the final blows to Voldemort.
Neville is a pure-blood wizard born to Frank and Alice Longbottom, who were prominent Aurors and also members of the Order of the Phoenix during the first war against Lord Voldemort.
