Old/Young Dumbledore Comparison
The main difference between teenaged Dumbledore and the Dumbledore of the Harry Potter books is the difference in their egos. When he was young, Dumbledore knew he was smart, smarter than all of his peers and more than a few adults in his life, but he did not have the maturity or perspective to avoid cockiness. He acts as though he is infallible, not letting himself consider that he could be wrong about, say, Grindelwald’s true nature or his treatment of his sister, and he refuses to change his mind until things go horribly wrong. As an older man, Dumbledore knows his strengths but is also able to recognize that he can make mistakes, one that can carry disastrous consequences; his attitude is summed up in his quote: “I make mistakes like the next man. In fact, being - forgive me - rather cleverer than most men, my mistakes tend to be correspondingly huger.”
There is also a strong difference in Dumbledore’s tolerance of others when he is a teenager and when he is older. As an adult, Dumbledore is a champion of Muggle rights, as well as a proponent for werewolf tolerance and respectful treatment of centaurs and mermaids. As a teenager, his feelings are a bit more complicated. Because Muggles were responsible for attacking his sister (and in turn, his father’s arrest and his sister’s ensuing insanity), he holds a grudge against them and silently considers them to be more ‘barbaric’ than wizardkind. When his sister’s insanity led to his mother’s death, I imagine his anti-Muggle feelings would only have been fueled by his sense of loss, and Grindelwald’s arrival would have fanned the flames. While I doubt he ever considered systematic mistreatment of Muggles or harming them for being what they are, I imagine when he was working with Grindelwald, their plans included treating Muggles as ‘lesser’ than witches and wizards and making them into a lower class. Not until Dumbledore’s actions cause his sister’s death would he realize that he could be just as barbaric and cruel as anyone else.
The other crucial difference is that younger Dumbledore desires power where his older self is hesitant to trust himself with it. Because he was a talented and ambitious young man, teenaged Dumbledore was eager to break free from his tiny hometown and see the world, as well as plot with Grindelwald to lead the wizarding world to a new age. Part of it is youthful recklessness and his strong ambition, but it also is partly his ego getting ahead of himself. His reckless quest for power is what lets him stand by Grindelwald and also gets him deeply entrenched in their plans for ‘The Greater Good’; when those plans lead to the death of his sister, the guilt Dumbledore feels is so great that he can never trust himself to seek power again. Even a century later, Dumbledore feels that if he becomes too ambitious, he could easily lose control and go back to his careless ways from his youth.
There is also a strong difference in Dumbledore’s tolerance of others when he is a teenager and when he is older. As an adult, Dumbledore is a champion of Muggle rights, as well as a proponent for werewolf tolerance and respectful treatment of centaurs and mermaids. As a teenager, his feelings are a bit more complicated. Because Muggles were responsible for attacking his sister (and in turn, his father’s arrest and his sister’s ensuing insanity), he holds a grudge against them and silently considers them to be more ‘barbaric’ than wizardkind. When his sister’s insanity led to his mother’s death, I imagine his anti-Muggle feelings would only have been fueled by his sense of loss, and Grindelwald’s arrival would have fanned the flames. While I doubt he ever considered systematic mistreatment of Muggles or harming them for being what they are, I imagine when he was working with Grindelwald, their plans included treating Muggles as ‘lesser’ than witches and wizards and making them into a lower class. Not until Dumbledore’s actions cause his sister’s death would he realize that he could be just as barbaric and cruel as anyone else.
The other crucial difference is that younger Dumbledore desires power where his older self is hesitant to trust himself with it. Because he was a talented and ambitious young man, teenaged Dumbledore was eager to break free from his tiny hometown and see the world, as well as plot with Grindelwald to lead the wizarding world to a new age. Part of it is youthful recklessness and his strong ambition, but it also is partly his ego getting ahead of himself. His reckless quest for power is what lets him stand by Grindelwald and also gets him deeply entrenched in their plans for ‘The Greater Good’; when those plans lead to the death of his sister, the guilt Dumbledore feels is so great that he can never trust himself to seek power again. Even a century later, Dumbledore feels that if he becomes too ambitious, he could easily lose control and go back to his careless ways from his youth.