The titular character of the Harry Potter series should have, all things considered, become a dark wizard — which was precisely the outcome that Albus Dumbledore was afraid of. The Boy Who Lived proved himself to be an anomaly with his enduring goodness throughout his years at Hogwarts. Yet, with all the horrible things that happened to him when he was an infant, it would have been no surprise if he had sought out power and domination, especially since this is what most Harry Potter characters did in these circumstances.
Harry was born into a loving home, but he could only enjoy it for one short year. When Lord Voldemort killed Lily and James Potter, their surviving son was sent to live with Vernon and Petunia Dursley, and they showed him none of the affection he had been used to. The Dursleys suppressed Harry's magic and abused him if he showed any sign of being different. Their son picked up on this treatment, and as he grew, so did the abuse toward his cousin. Starved, beaten, and suppressed, Harry had every reason to grow resentful and aggressive. Still, the hero of Harry Potter remained just that — a hero.
Harry's Circumstances Would've Made Him The Perfect Villain
Harry's story wasn't unlike the origin story of several other Dark wizards in Harry Potter. Lord Voldemort had also been raised as an orphan in a loveless home. Severus Snape had sought Dark magic to gain power after a childhood of abuse and neglect from his Muggle father. Even Dumbledore's family tree and history led him down a path of darkness after Muggles attacked his sister, and his father was sent to die in prison after getting revenge. Ultimately, injustice in the wizarding world has a way of turning out villains.
Years of mistreatment by the Dursleys would have been enough to make Harry wish to punish Muggles, and the murder of his parents could have inspired a desire for domination over the wizarding world in Harry Potter as well. Additionally, Voldemort's attack granted the boy with power that the Death Eaters would have killed for. Harry had everything he needed to be the most powerful dark wizard there had ever been, so it would have been easy to assume he would do just that.
Why Dark Wizards Thought Harry Would Be The New Dark Lord
When Lord Voldemort heard the prophecy in Harry Potter describing the person who would have the power to destroy him in Harry Potter, he assumed it described a similarly evil rival. He believed that the morality of wizards like Dumbledore made them weak, so only someone willing to achieve the power of darkness would ever truly stand a chance against him. For this reason, when Voldemort was destroyed by Harry that fateful Halloween, many of his followers thought Harry was a powerful dark wizard— even as an infant.
The Harry and Draco were also distantly related, so it only makes sense that he was eager to befriend Harry and secure himself within the inner circle of the next wizard to gain power in the wizarding world. Of course, Draco quickly learned in Harry Potter that the Boy Who Lived was far from the pure-blood champion he had expected.
Dumbledore Tested Harry's Morality In Sorcerer's Stone
Albus Dumbledore was also unsure of the kind of person that Harry Potter had become when the boy started school in Harry Potter and the Sorcerer's Stone. The memories of Severus Snape suggest that the heaster had been getting reports on Harry's behaviors from his teachers and was pleased to hear that he was a bright, modest, and kind child. Still, Dumbledore set up a test that would perfectly gauge Harry's morality, as referenced in the Half-Blood Prince book:
“You are protected, in short, by your ability to love!” said Dumbledore loudly. “The only protection that can possibly work against the lure of power like Voldemort’s! In spite of all the temptation you have endured, all the suffering, you remain pure of heart, just as pure as you were at the age of eleven, when you stared into a mirror that reflected your heart’s desire, and it showed you only the way to thwart Lord Voldemort, and not immortality or riches. Harry, have you any idea how few wizards could have seen what you saw in that mirror? Voldemort should have known then what he was dealing with, but he did not!"
In Sorcerer's Stone, Dumbledore brought Nicolas Flamel's Stone to Hogwarts and set the desire revealing Mirror of Erised to protect it. The Mirror would only give the Sorcerer's Stone to someone who, in their heart, only wanted to protect it and not use it. When Harry chose to go through Fluffy's trap door to stop anyone from getting the Stone and successfully gained possession himself, Dumbledore knew that Harry was pure of heart. Despite many new sufferings, that purity of spirit endured year after year in Harry Potter, proving to Dumbledore that instead of creating a villain, Voldemort had produced a force of good so powerful the Dark Lord wouldn't stand a chance.
Lily's Love Didn't Just Save Harry's Life, But His Morality Too
Harry was disappointed to learn in Harry Potter that the power that he possessed that the Dark Lord knew not was love. Voldemort had also disregarded this same power, but time and time again, love proved to be an effective weapon. It was Lily's love that allowed Harry to survive the Killing Curse when he was an infant and again at 17. But, the love Lily demonstrated for her son did something far more critical—it guarded Harry's soul.
In Harry Potter, love is the sure way to save someone from darkness. When Dumbledore was set on his path of domination with Gellert Grindelwald, his love for his sister saved him. Severus Snape wanted only power, and he sacrificed his friendship with Lily to chase it. Regardless, when she was killed, his love for her drove him to dedicate himself to bringing Voldemort down. For Harry, even though he couldn't his mother's embrace, her love was deeply engrained in his very soul.
When Lily sacrificed herself to save Harry without any attempt to preserve herself with a wand, it enacted a rare kind of magic that protected Harry's life from Voldemort. However, it also protected Harry's soul. No matter what darkness existed around Harry or even within his body (like Voldemort's soul fragment), the boy's heart could not be marred. Love guarded Harry's innocence in Harry Potter, ensuring that he would never become the villain that circumstances wished to bend him into.
