The general consensus around Hogwarts was that Gilderoy Lockhart's time as Defence Against the Dark Arts Professor had been a complete waste of time. However, those people hadn't been properly introduced to one Vincent Crabbe of Slytherin.
The teen had taken a great lesson away from Lockhart's term and had spent the better part of two years into being able to being able to enact his plan. This was mostly due to the fact that Crabbe needed that time to be able to wrap his head around the mechanics of the two spells involved. And because he'd needed to use a dictionary to be able to understand the long words involved.
But with the first days of his fifth year behind him he decided to experiment. He'd already picked out a victim – Ravenclaw first year "Loony" Luna Lovegood – and was preparing to strike. If the rumours around Slytherin were true, she was already turning into a pariah in her house due to her quirks, so if he failed then hopefully she wouldn't be believed. At least for long enough so that he could talk Malfoy or Snape into rendering assistance because he'd made an "honest mistake."
"Hello, Mister Goyle," greeted Luna as she noticed his presence.
Nothing for it now then as his attempt at remaining silent had failed, thought Goyle as an evil grin crossed his face. "Imperius," was all he said in reply as he jabbed his wand in her direction. He had put all his not-to-considerable will into the spell and was rewarded with the draining of emotion from Luna's face as the spell took hold.
A few hours later, a dishevelled Vincent gave the vacant classroom a once over for evidence before turning to the form of Luna. She was blankly and obediently doing up the last buttons of her shirt, the smell of sex still strong.
"I'd ask if you enjoyed that Loony, but I doubt you'll remember in a few minutes anyway," Crabbe commented in an amused tone. Hopefully he remembered how this next part went, as he'd only gotten it right recently and didn't really want to do anything too harmful. Loony was a pureblood after all, even she weren't a good one.
Stepping towards the door to the classroom, he pulled out his wand again and pointed it at Luna. Once he'd gotten to the corridor, he jabbed his wand at her and uttered 'Obliviate' and screwing up his face in concentration.
Once he was sure he'd done the right thing he released the Imperius and silently closed the door as Luna blinked back into consciousness. A look of confusion crossed her face, "… What's going on?"