How History Repeats Itself
In many ways, the events of the Fantastic Beasts series mirror the events of the Harry Potter series. Most notably, though, is how the battles between Harry Potter and Voldemort closely resemble that of Dumbledore and Grindelwald. While the minutia may be different, such as the time period or the characters’ histories, the overall story arc is almost identical.
For starters, both warring pairs share a unique and immensely powerful bond. In Fantastic Beasts: The Crimes of Grindelwald, Dumbledore claims that his relationship with Grindelwald went beyond the bounds of brotherhood, hinting to the audience about a possible romantic relationship. In addition, after scheming together for months, the two formed a blood pact, promising not to move against the other. While Harry and Voldemort never promise to not fight each other, they do struggle to actually kill each other throughout all seven Potter novels. Until Harry Potter and the Goblet of Fire, Voldemort cannot even touch Harry due to the latter’s protection from his mother. Also in Goblet of Fire, their wands recognize the twin cores and lock together, causing a Priori Incantatem effect. In Harry Potter and the Deathly Hallows, their spells lock together and the two wizards must, essentially, push their spells at the other. Not exactly a normal wizard’s duel. In addition, Harry unwittingly lives his early life as one of Voldemort’s Horcruxes. This relationship is certainly different from that of Dumbledore and Grindelwald, but it is just as powerful and in many ways, just as personal.
Furthermore, it is this powerful bond that ultimately leads to the showdown that brings about the downfall of Voldemort and Grindelwald. In Deathly Hallows, it takes Harry, Hermione, and Ron to track down all of Voldemort’s Horcruxes, plus the entire Battle of Hogwarts in order to get Voldemort in the right place at the right time. Despite all of the help Harry receives and the jeers from Voldemort about Harry letting others die in his place, in the end, it was the one-on-one battle between Harry and Voldemort that finally vanquished the Dark Lord. Similarly, Dumbledore is the sole person credited for Grindelwald’s imprisonment. Although we do not know the exact details of the epic fight yet, we can assume it, too, was a one-on-one fight. Plus, just like how Harry had help tracking the Horcruxes, we know that Dumbledore utilizes Jacob Kowalski, Newt Scamander, and Tina and Queenie Goldstein to help him stop Grindelwald.
Finally, in both cases, the fight seems to come down to good versus evil in a rather blunt, black-and-white manner. Now, one could argue that Dumbledore was never wholly good, pointing to the fact that in his younger years, he helped Grindelwald plan for global dominance. In fact, even Harry could be seen as slightly evil, having used various Unforgivable Curses in Deathly Hallows. Still, Grindelwald and Voldemort are both supposed to represent the epitome of evil. They kill indiscriminately and always work to advance their own agenda and wants. They claim their actions are meant to better society as a whole and yet often marginalize and/or destroy the minority group. In contrast, Harry and Dumbledore are painted as the heroes who prevent this horrendous outcome. Through that lens, the fight between Harry and Voldemort or Dumbledore and Grindelwald is a fight between good and evil.
Now, the two battles differ when you begin to consider the various smaller details. For example, Dumbledore and Grindelwald were close in age and were childhood friends, whereas Voldemort was targetting a child, as per a prophecy. Plus, Voldemort and Grindelwald, despite both being the most notoriously evil wizards of their generations, had very different styles. The same can even be said for Harry and Dumbledore. In the end, though, what do you think is more important: the overarching ideas and motivations or the more detailed aspects?