Author's Note: I do not own FMA, Harry Potter, or their characters. This is AU and takes place after the fifth book.
The Best and the Worst Teacher Ever
If asked, Edward Elric would not admit to being highly amused by the Hogwarts students' reactions to Colonel Mustang. However, that didn't stop it from being true. The students either loved him or hated him, and none of them understood him at all. As both a student and the Defense Against the Dark Arts classroom assistant, Ed had the unique opportunity of being able to eavesdrop on the rest of the students with ease.
Mustang was either the worst DADA teacher they'd had or the best, depending on who was giving the opinion. The muggle born students universally liked Mustang for the most part. His lessons were practical and made sense to them. The students who had been born in the wizarding world had more mixed reactions. The snootiest of the purebloods hated him. He didn't put up with any of the prejudices or ideas about how things should work. Many of them were puzzled by his teaching style and what he decided was important to teach. The one group that was always disappointed in Mustang was the girls who had plans to seduce him for a batter grade. That was a hopeless cause.
And it was great fun watching Mustang get frustrated without being the target of those frustrations. He and Mustang might agree on a lot of things, but even Mustang would admit, he was much better at dealing with the perils of life than any of these students. That, and there was something satisfying about seeing the idiot trio of Granger, Potter, and Weasley serve detention for snooping around Mustang's office one too many times. Someone had to teach those three a lesson before they got themselves killed.
Theme: Teaching a Lesson