AN: This is my first fic, so I apologise if it's a bit muddled. This is currently a oneshot, but I can write more if that's what's desired. Reviews are like biscuits to me - always wanted and greatly appreciated
Disclaimer: I only own this story. If I owned Harry Potter and/or Sherlock, they would be much worse than they are.
"My name is Professor Holmes and I will be your new Defence Against the Dark Arts teacher."
The students blinked up at him, already used to not having a teacher for very long. To them it didn't matter who he was, he would be gone by the end of the year, just like all the rest. Professor Holmes picked up on this lack of enthusiasm instantly, and suddenly told them to push the desks to the edge of the room and to pick up their wands – today was to be a practical lesson.
Sally Donovan and Phillip Anderson were in their sixth year and were bored with DADA: the teachers were never around long enough, resulting in gaps in their knowledge. They expected very little from this teacher. With a sigh they hauled their desks to the edge of the room and, dumping their bags on top of the desks, pulled their wands from the inner pocket of their robes.
"I hope we're not doing curses again" muttered Anderson, trudging back to the middle of the room.
Sally nodded and tucked a stray piece of hair behind her ear. She didn't mind curses so much, she was good at them, and found the after effects fascinating to study – she had been put in several detentions for hexing first years in the past, but now she looked forward to DADA lessons. She wanted to be an Auror when she left, or maybe a Healer.
Professor Holmes practically bounced to the front, his movements erratic as his long robes billowed out behind him. He sat on his desk, hands steepled under his chin.
"Today we're practicing duelling." he announced, gauging the reaction of his class.
They were less than impressed – the last teacher that attempted duelling was Lockheart, and he turned out to be an idiot. The students muttered to each other, rolling their eyes at the new teacher.
"But-" interrupted the Defence Professor, "I'd like you to cast a shield before your opponent casts their spell."
A lone hand was raised amongst a sea of lost faces. The tall man nodded and asked for a name before the question was asked.
"Peter Jones, sir, but how do you tell what someone is casting before they cast it?"
"By observing. You look at their body language, their arm position, the shape of their lips if they are casting a verbal spell. You see and you deduce. Different spells have different wand movements, and you can at least attempt to work out what the spell will be."
The class nodded, comprehension dawning on a few of their faces. Sally Donovan thrust her arm into the air, nearly hitting Anderson in the face.
"Like Confringo and Langlock sir? One has a stabbing motion, while the other is a small circular motion over the opponent's mouth?" she blurted, anxious to see if she understood.
"10 points from Griffindor for interrupting, but yes the concept is correct. If you get yourself into partners to practise – I don't expect you to get it immediately, but hopefully some progress will be made. Nothing to dangerous please, I don't want to make a trip to the Hospital Wing on the first day of term."
Curses, jinxes and hexes flew around the room, and shields were thrown up in response. Many of the shields were ineffective, ill-suited to protect against the offensive spells cast at them. A few of the shields worked, often to the surprise of the caster. Professor Holmes prowled through his students, giving tips where needed, and adjusting wand movements to get the best effect. In his opinion the class was slow to pick up what spells were being used, many students sticking to the same old spells and using them repeatedly, lacking originality. A few impressed him, one sixth year used a particularly impressive summoning charm to pull an ink pot from his desk, hitting the target and coating them in ink. This provided sufficient distraction for a tripping jinx, followed by an expertly cast expelliarmus. The student received 20 points from the professor and a filthy look from their opponent.
By the end of the lesson, many of the students had made some progress, and the DADA teacher, while glad they had knuckled down and put in the effort, expected two feet of parchment on why deducing spells before they were cast is helpful in a combat situation by the next lesson.
Still buzzing from the lesson, the students piled out of the room at the sound of the bell, leaving the defence classroom quiet once more. Professor Holmes ran a hand down his face – he had to face a whole year of babbling students and marking. He sat down at his desk and began to shuffle round his papers when he heard footsteps interspersed with the clack of a crutch on the cold stone floors.
The flying instructor poked his head around the door, smiling when he saw the defence professor.
"Morning," he said "Would you like a cup of tea?"
The DADA teacher took one look at the new face, his eye sweeping over the tanned skin, muscular build, and crutch.
"Holyhead Harpies or Chudley Cannons?" he asked.