Obligatory Disclaimer: I own nothing - it's all J.K. Rowling's.
1 - Neville
He knows it was a mistake as soon as the words leave his mouth.
"CRUCIO!" the professor roars, and the spider wrenches – that's the word that pops into his head – wrenches and shrieks and –
He sees, in his mind's eye, his parents – his parents wrenched and twisted and screaming, screaming, and he tries to look away, look anywhere else, shut his eyes, but the sound of the shrieking, pierces his brain – his mum and dad – no, don't think of that – no...And as if distant, he hears behind him, "Stop it! Can't you see it's bothering him?"
And the screaming stops, and he opens his eyes and swallows. His hands are shaking.
He takes a deep and shuddering breath and sits down.
Later, after class, the professor apologizes gruffly, gives him a cup of tea, and presents him with a book on aquatic herbs, telling him to keep it. He stuffs the book deep into his bag and resolves not to ever read it.
But a while later, he pulls it out again. Magical Water Plants of the Highland Lochs. It's an old book, with that musty smell to it. The illustrations are faded but intricate. A flash of memory – the spider – but he blinks, opening the book to a random page. Mandrakes. Mentioned in passing in a paragraph on some other herb – he doesn't notice what…
He smiles faintly at the memory of his first encounter with the plant. He had passed out, yes, but later, when he approached the professor to apologize and perhaps even tell her about his garden back home (his grandmother disapproved, of course, but she couldn't stop the plants from growing, could she?), she smiled and patted him on the head, saying, "We'll make a Herbologist of you yet, young man."
He smiles again and turns to another page. Gillyweed. Interesting…and he could probably find some around Hogwarts. The lake, after all, is right there.
Tomorrow. Tomorrow he'll get his boots, and his bucket, and during his free period, he'll find some gillyweed.
He lets out a small and contented sigh, almost unnoticeable, and absorbs himself in the book.
Later, when he visits his parents in St. Mungo's, he thinks of the looping and curling of fronded devilkelp. And it becomes easier to hold back the tears.