The first few classes went well.
Presenting a boggart to a classroom full of children was always a risky thing to try and perhaps not his best idea but Remus was determined that it was still an important lesson so after much thought he had decided to go through with it.
He had tried to be careful. Taking precautions to protect students who were known to have upsetting things in their past which might cause problems, giving them the option to skip the class if necessary and being prepared to step in, in case anything went wrong. All things considered it really was going well.
A few clowns, in inordinate number of spiders, rats, snakes, teachers (A few Snapes) all normal things for kids to be scared of. All simple irrational fears for them to work through in a safe environment where they could amuse themselves in the process. He had had his doubts but after a few classes Remus was ready to declare the boggart a success.
Then the fifth year Huffelpuff class came in.
It started off fine, just as the others had.
Then Mary Lipscomb had stepped up. Her poor hands shaking as she raised the wand. Eyes fixed on the cupboard with absolute terror plastered on her young features.
For a moment the professor considered stepping in and asking Mary to sit this out, concerned that perhaps there was something in her childhood that he was not aware of. Something that might not be appropriate to display here in a classroom in front of all her peers but the young woman squared her shoulders and nodded for him to open the door so Remus took a chance, confident that the young woman would have asked to be excluded if she really needed to be.
He opened the cupboard.
The boggart emerged.
At first Remus wasn't sure what he was seeing.
The whole room froze. A quiet mix of confusion and terror fell over them.
Until the boggart opened its mouth. The mouth of a child, Japanese by the look of him, with dark eyes trained directly on Mary and skin that appeared sickly and blue. The sound that emerged was a sickening screech.
Mary screamed, not even making an attempt to cast Riddikulus, instead spinning in place and running for the door in a full sprint.
This was not what shocked Remus, as another student jumped in to take over with the boggart, quickly driving it into the cupboard again. He fully understood that some of his students would struggle to confront their fears first try. Mary wasn't actually the first student he'd had run away.
What shocked him was that when Mary ran, ever other muggle-born in the room ran with her. All of them sharing the same look of unbridled terror plastered to faces that were now deathly pale.
The students from Wizarding families remained where they were. Disturbed by the creepy boggart child but otherwise unaffected. Before he had a chance to follow his runaway students out into the hall to round them up the voice of Toby Rodgers came echoing back into the classroom, a slight quiver of fear mixed with anger in his tone.
"Mary I don't blame you for choosing that, I really don't, but don't you ever, ever put me in the same room with the fucking grudge ever again!"
I don't know if the ghost from the grudge has an actual name but if it does I don't know it and I have always just referred to it directly as the grudge. I realise that there were actually two ghosts but at different times I have referred to both individually as the grudge and personally feel the kid was the creepier of the two.