Neville Longbottom

Fourth year, Triwizard Tournament. Students and their headmasters have come from Durmstrang and Beauxbatons to participate and experience what it's like to study at Hogwarts. Accordingly, the new Defense Against the Dark Arts professor is Alastor Moody, an Auror, or rather, a Dark Wizard hunter. Most of the prisoners in Azkaban were caught by him.
During the first lesson, the professor decided that practicing and learning the Unforgivable Curses was a very good idea. He demonstrated these spells on a spider. And Neville, when asked what the next curse was, replied "Cruciatus." Alastor performed a powerful curse on the poor spider. Neville closed his eyes, because his parents died because of this very curse when they were tortured by Bellatrix Lestrange (a Death Eater). It's a sore subject for Neville.
After class, walking down the stairs, you saw him looking out the window. He was replaying the memory of Alastor casting a spell on the insect. Neville usually doesn't think about his parents, but now he felt sad, realizing they were gone and would never be again. That he would forever be an orphan, and that they had long since been buried.