Dread filled Neville as he eyed his cauldron wearily. Neville could freely admit that he was horrendous at potions, he had long accepted this. It didn't stop him wishing that, for once, he might finally get a potion correct without Hermione having to mutter in his ear.

He gulped audibly as Professor Snape made his way around the class, taking a moment to leer at Neville.

Glancing at the time, Neville realised that he only had minutes left until the potion was meant to be complete, and his own potion was completely of colour! Desperately, he scrambled for ingredients, hoping that somehow he might be able to remedy this potion.

Looking over the labels before squinting through the condensation filled room to look at Snape's spiky writing, he decided that this would most likely be his best chance, so he quickly piled all the ingredients in, daring to look hopeful as he watched the slowly changing potion.

Severus had moved to his desk after a survey of the nervous fourth years currently working on their potions. He was sure for now nothing too drastic would occur. Though he would have to check again shortly as Longbottom happened to be in this class.

"Er, Professor?" A timid voice asked, barely audible over the bubbling of cauldrons.

Severus pinched the bridge of his nose in aggravation, trying to muster up the will power to look at another idiotic student.

"PROFESSOR!" Another student, female this time, shrieked.

Severus glanced up at the shrill voice, recognising the panic in the tone and coming to the assumption that Longbottom had blown up a cauldron or the like, but he looked up in time to see an ominous mist slowly filling the room, having already taken out the students nearest a completely obscured cauldron in the back of the room. Longbottoms, of course.

"Run!" He yelled to the Slytherins and Gryffindors who weren't currently collapsed on the floor (he hoped they were just asleep, it wouldn't do well to report the deaths of several students), he made sure the few students at the front of the class who hadn't be hit by the gas erupting from Longbottom's cauldron were out of the class, before backing out himself and attempting to vanish the mist.

After a few tries, he decided another approach would need to be taken.

"Wait out here." He told the small number of safe, but rather panicked looking, students before pointing to Tracey Davis and Lavender Brown and commanding them to get the Headmaster and Madame Pomfrey, then briskly casting a bubble charm over himself, he made his way back into the mist filled class room.

It was impossible to see, of course, and Severus realised he would have to clear the mist somehow if he wanted to help the students. After a few attempts of vanishing and transfiguring it he decided to simply cast water over it and see if this had any effect.

Thankfully, this managed to banish a large portion of the mist (though he supposed the students would now be rather drenched, and he would have to be careful not to slip on the sodden concrete floor) and he could finally see the students.

He nearly fainted in shock when he saw what had happened.

"Severus!" The Headmaster said, swiftly making his way through the door and looking at the Potion Masters shocked expression in confusion, before looking down at the happily sleeping students in astonishment.

On the floor, lay a number of Slytherin and Gryffindor fourth years; Pansy Parkinson, Daphne Greengrass, Blaise Zabini, Vincent Crabbe, Gregory Goyle, Draco Malfoy, Dean Thomas, Seamus Finnigan, Hermione Granger, Ron Weasly, Harry Potter and, obviously, Neville Longbottom, and every single one of them, appeared to be infants.

"Severus." Professor Dumbledore repeated again, looking down at the tiny, sleeping students. "What happened?"