I wrote this a few years ago and at the time I hadn't seen anything like it, I always smile now when I see the tumblr post about something similar to this that pops up on my news feed every now and again. Completely original ideas for the HP fandom are impossible to come up with.
Harry had been promoted to the Head of the Auror department and instantly his troubles increased ten-fold. Such was his fame and popularity, the number of applications from that years graduating Hogwarts (and other schools) students had quadrupled simply because people wanted a chance to work under the direction of The-Boy-Who-Lived.
While the grades for each applicant was up to standard, he worried that many of them would not have the speed, skills, level headedness or swift reactions times that would keep them safe on the job. While he knew that the lengthy training program would weed out the less suited applicants, he didn't want to miss potentially excellent aurors that were bound to be amongst the mix of average trainees in such a large group. He also didn't want to have to delay a trainees' chance at finding a position in a much better suited field as well as dealing with the disappointment that they would inevitably have after he cut from the program.
He spent weeks agonising over safe ways to figure out how he would be able to tell who could and couldn't do the job as he spent hours every night looking through all the applications, but he was stumped. So were Ginny, Ron and even Hermione when he asked them for ideas. None of them could come up with anything new and realistic.
It wasn't until he went to Dudley's Son's birthday party about four weeks after he first started searching for a solution that he figured out what to do.
That afternoon he went to visit George to ask him if it would be possible to develop his idea. George had loved it and got to working on it that evening.
A few months later, the Auror department took the first delivery of the new Weasley's Wizard Combat Cloaks.
They had been based on the muggle children's game, laser tag. However, instead of a gun and a vest that made noises and lit up when it got hit, it had a wand that shot placebo spells and a cloak that not only showed a different colour for each spell so an accurate analysis could be made of the attack and defence at the end of a training session, but it also sent a small shock or temporary paralysis through the witch or wizard wearing it to simulate a real spell and how that would affect them in any real life situation.
Needless to say, they became a permanent fixture in the Auror training sessions and George had the most requested and top selling Christmas present for the next three years.