In some important ways, the power of friendship is one of the most enduring--and endearing--themes of the entire Harry Potter saga. Obviously, there’s the strong bond between Harry and his companions Ron and Hermione, but there are also numerous other pairings that occur throughout the films and the books, both among the students and among the faculty.
However, it has to be said that there are also quite a few friendships that never took place but which, in all fairness, probably should have, considering how alike some of the characters are in terms of their temperament and their behavior.
Sprout And McGonagall
This is a friendship that is truly delightful to imagine. Can one envision a more incongruous pairing that Sprout and McGonagall? While Sprout has a very salt-of-the-earth sort of persona, McGonagall is much more prim and proper about how she does things and in how she presents herself to her students (she really was the best, wasn't she?). However, can anyone doubt that the two of them would make a truly splendid pairing, and it would have been particularly amusing to see the two of them having tea together.
Aberforth And Hagrid
Aberforth is one of the more enigmatic members of the cast, since there’s much that remains unclear about his personality and motivations until relatively late in the series (the same is also true of his brother Albus). However, one does eventually learn that he’s a rather down-to-earth sort of fellow, one who’s a bit more grounded in his sensibility than his brother Albus. This would make him a great friend to Hagrid and, who knows, he might have even been able to tame some of Hagrid’s more outlandish habits when it came to his magical creatures.
Lupin And Neville
This is one of those friendships that it’s hard to see why it wasn’t more of a focus. After all, both Neville and Lupin have their own burdens to bear, Neville as a result of his parents' torture and subsequent madness, and Lupin because of the curse of being a werewolf.
What’s more, there seems to be a genuine sort of understanding between the two of them, and they each could have provided a measure of comfort to one another, since they were both very sensitive people.
Dudley And Crabbe And Goyle
Poor Harry has quite an unpleasant life living with his cousin, in part because Dudley is just so plain obnoxious. Unfortunately, going to school is only somewhat of an escape, because he has to contend with the likes of Crabble and Goyle, who are very much like Dudley in their bullying ways and their general dimness. Though the three of them never meet, this is one of those friendships that would really seem like the most natural thing in the world, though they probably would have eventually turned against one another.
McGonagall And Snape
Now, some might sneer at this one, particularly since McGonagall and Snape are so very different and, while this isn’t made clear, it seems that McGonagall probably looks at Severus with a bit of distrust (due to his past affiliations with Voldemort). However, there’s more in common between them than appears at first, since both seem to genuinely want the best for both Hogwarts and the students who go there, even if they have very different ways of expressing it to others.
Umbridge And Bellatrix
In the entire history of this franchise, two characters are the most unpleasant, and those are Bellatrix Lestrange and Dolores Umbridge (though Bellatrix is probably Voldemort's better lieutenant). Both of them really do seem to enjoy torturing others in both the physical and mental sense, and neither seems to have much interest in developing a moral compass or anything remotely resembling a conscience. They would definitely have made a formidable friendship team, and while they should have gotten together, most readers and viewers are probably grateful that they didn’t.
Percy And Aunt Petunia
While most of the Weasleys are mostly pretty easy going when it comes to rules and procedures, that is definitely not true for Percy. In fact, he seems to think that rules are the only things that matter in the world and that it doesn’t matter who one hurts in the process of following them. Petunia is similarly stuck-up, and she carries a bit of a chip on her shoulder as far as her sister is concerned (though much more is revealed about this in the books than the movies).
While theirs would certainly be a very negative friendship, it can definitely be seen as one that should have happened.
Uncle Vernon And Slughorn
Like his wife Petunia, Vernon has a pathological aversion to anything to do with magic (and pretty much everything else that he can’t really seem to explain), and he was truly horrible to Harry. While it might seem counterintuitive to think that he might have had a friendship with the likes of Horace Slughorn, it’s pretty likely that, at the very least, he would admire Slughorn for his ability to worm himself into the good graces of the most famous people (even if he had to sometimes do bad things to get there). If there’s one thing that Vernon does respect, it’s status.
Xenophilous Lovegood And Sybil Trelawney
It is nothing less than shocking that a friendship between Xenophilius and Sybil didn’t happen at some point in either the books or the novels (it's also a miracle that Sybil didn't get fired, even when she should have). In fact, it’s hard to think of two characters who had more in common than these two. They both seem to be just a little bit left-of-center (or way in the outfield, depending on one’s perspective). If nothing else, it would have been interesting to see the two of them go at it in an attempt to prove to the other that they had a firmer connection to the spirit world.