I don't own Harry Potter. Idea came from Ausar the vile
What Sirius had to learn the hard way was getting to places at Hogwarts was difficult to say the least. There were only 142 staircases at Hogwarts, but no staircase seemed the same. Some went to different places on different days, some had steps that seemed like they were solid but if you try to step on one you go through the step. The first few days Sirius was late to three classes because he got lost.
Finally, after a tiring day, the class that Sirius was most excited for was here. Defense Against the Dark Arts. For some reason, first years don't have any classes with other houses except in this single class. Sirius hadn't gotten the opportunity to hang out with Severus or Lily for long because of school and they were in different houses. So when they walked into the classroom, they all sat together so they could talk and swap notes. Peter noticed the boy Remus Lupin and invited him over.
"Hello," said the Gryffindor. " I'm Remus, what are your names?"
After they introduced themselves, they started to talk, if fact, everyone was talking, until the teacher walked in. He was tall, and had the demeanor of someone who you didn't want to mess with.
"Hello class," said the teacher. "Now I hope you actually read the book, otherwise things will be very embarrassing for you."
Sirius was a little nervous, but he calmed himself down as he read the first five chapters in the book, more than recommended.
"Black," said the teacher. "How would you fight off a dementor?"
It was at this moment when Sirius started to panic. He didn't know the answer. He heard his dad talking about how Azkaban had dementors, but he didn't know how to fight them.
With nothing else to say he simply said," I don't know,"
"Disappointing," said the teacher," I would have hoped that one of you idiots would actually read."
"I did read the book, I just didn't get to any part about dementors," said Sirius.
"Do not talk back, five points from Hufflepuff." said the teacher.
Sirius was astonished. He didn't answer, knowing that if he said anything the teacher would probably dock more points. He saw Severus writing a note, which was passed to him. It said,"Dementors are a third year subject. I can't believe that the teacher gave you such a hard question"
This made Sirius angry to say the least. He wanted to yell some choice words at him. He couldn't believe that he was giving such a hard question. It got worse when he gave James a much easier question," What is Expelliarmous?"
"The disarming charm," said James, looking smug, despite answering a question that was in the first chapter.
All in all, Sirius was glad when the class was over.