A/N: Wrote this after seeing a gifset on tumblr. I don't own Harry Potter or Doctor Who, nor the characters.
The students were dotted about their classroom; some were messing about paying pranks and bewitching paper birds. The teacher was late, but everyone was excited they'd all heard rumours about the new teacher; several were glowing reviews, whilst others appeared terrified. There was a gaggle of girls in one corner, talking and giggling the occasional loud shriek was heard. The guys groaned and started talking in their seats; Harry and Ron were talking about Quiddich when a voice cut over their conversation.
"Another pathetic attempt at magic Longbottom?" Malfoy sneered looking down at the mess Neville had made, "This place has really gone to the dogs, letting in mudbloods and squibs." He said to his closest companions.
Harry stood up, "Don't use that word and leave him alone Malfoy."
"Why would I do that, Potter?" Malfoy drawled.
They bickered back and forth for a while, the rest of the classroom watched avidly, wondering who would win. Before long, one of them pulled out their wands and the first hex was sent. The boys were snarling each trying to one up the other and through it all, sitting by herself at the front of the classroom was Hermione Granger. She was lost in thought about a transfiguration theory was a spell whizzed past her head, nearly hitting her; she flinched and turned around to find Harry and Malfoy fighting.
"Enough!" She shouted pointing her wand and freezing them both, "You're acting like first years! Harry, Malfoy was trying to get a rise out of you, stop falling for it." She turned to Malfoy, "Stop being so immature, we get it you are rich and you have an inferiority complex, I highly doubt anyone cares any more, if they ever did!" Malfoy stared at her livid but he couldn't do anything as she paused taking a breath, "Now, I'm going to let you go now, if you start fighting again I will send you both to the hospital wing. Is that understood?" She asked looking at booth of them for a moment before releasing the spell. The both gasped in air and started at her incredulously, what on earth was up with Hermione, she rarely snapped. The boys all glanced at each other wondering who was to blame.
"I do not have an inferiority complex Granger." Malfoy growled.
"Could have fooled me." She said shrugging, as Malfoy tensed ready to send another spell.
"Well now that was fascinating!" A new voice exclaimed. They all turned to look at the front of the classroom; there was a strange woman with blonde curly hair and a metal eye-patch sitting on the teacher's desk. "Oh, don't mind me, I'm Professor Song." She smirked as the classroom erupted with noise as everyone rushed to find their seats, they been looking forward to this. "Now then, Let's see." She looked over at Hermione, "You are Miss Granger, right?"
"Yes." Hermione squeaked, afraid of having points docked.
"Well done, that was impressive magic!" Professor Song smiled before waltzing down the classroom towards Harry and Malfoy. She had an air about her the made everyone pay attention to her.
"Professor, how long were you here for?" Hermione asked tentatively.
"All of it." Professr Song answered absently looking at the two boys, "Now, this is not good. Hmm, Mr. Malfoy and Mr. Potter please get up and sit at the front middle desk." She motioned for the students there to move. "Your punishment will be this, for the rest of the year you'll work together, I think we'll get brilliant results!" She exclaimed smiling, ignoring the class looking at her as if she was insane.
"Professor." Hermione asked again, "Will we be using defensive spells?"
The professor just smirked finishing her rounds and leaning back on her desk, "Spoilers, Miss. Granger, spoilers."
The class carried on that way, she would walk around the classroom, teaching them things and then would go off onto a tangent about space and creatures that no one saw, like the Silence, Nargles, the Daleks and The Umgubular Slashkilter
"Miss. Granger, if you could stay behind." She asked just before the signalling the end of class, and the beginning of lunch. Most of the students left excited, but Malfoy glowered and pushed everyone out of his way, Harry and Ron packed up slowly unsure if they should leave.
"It's fine, Harry, Ron. I'll meet you outside." Hermione said smiling.
"That was impressive magic Hermione, may I call you Hermione?" Professor song asked, smiling when she nodded. "I wanted to teach you a spell, it's the one I used earlier, I know you were dying to ask. It's a spell to conceal your presence, often used in conjunction with the disillusionment charm, which shields you from view. The disillusionment charm isn't foolproof, people can still see ripples in the air and if they focus they'll realise you're there. It's quite hand a handy spell, but it's tricky though I think you'd handle it. Do you want to learn?"
Hermione nodded eagerly, her eyes lighting up at the thought of new knowledge.
"Very well, the incantation is as follows, 'Celare'." She said pronouncing it slowly and correcting Hermione's pronunciation a tad, "CEL-AR-EH". She then demonstrated a complicated wand movement, before walking Hermione through the steps, eventually she got it, though it was very weak to begin with. Professor Song smiled, "Keep practising and come back if you want to learn anything else." She said letting her out of the classroom. Harry and Ron were still waiting outside and had been joined by Luna who was staring dreamily up at the ceiling.
"Hello, Hermione. You're covered in wrackspurts." Luna greeted her, pausing and cocking her head to the side and looking at the Professor and gesturing to her blonde hair. "I take it you just taught her a new spell, they are after all your wrackspurts."
"That I did Luna." Professor Song said delightedly, "Do want to walk to Lunch together?"
Luna smiled and they started an animated discussion about whether or not there were any vashta nerada living in the library.
The trio looked after the duo shaking their heads, "She's bonkers!" Ron exclaimed.
"Maybe but she's a good teacher." Hermione mussed.
Harry just shook his head, "Ginny was telling me that she'd told her a story about her husband who was over 900 years old!"
Hermione furrowed her brow, "That's not possible, even for wizards."
"Maybe he's a Crumled Snorlak thing," Ron said interrupting, "Can we get to lunch?"
The others laughed and they followed the duo down to the Great Hall.