The worst news she'd heard since finding out they couldn't stay at Hogwarts over the summer was that Professor Snape was to be her Occlumency teacher.
He was a bully. An immature, standoffish, cruel bully. There was no other word for him, not when he went out of his way to humiliate Gryffindors, to specifically target her brother, to show a spectacularly unfair bias for his precious Slytherins.
Plus, he ignored Calla completely. He'd literally never, in the full year that she'd had his class, said a single word to her. He would just give her passing grades on all her assignments and move on to scare Neville to tears again.
So, really, as she stood outside the door to Professor Snape's office, she wondered how Dumbledore even got him to agree to this. She only agreed because she didn't want to be a freak for once in her life, because she just wanted to be normal--or as close to normal as she could be while still being the girl who lived.
Also because she'd studied that massive book all summer long, and she wasn't going to have read all that for nothing.
Taking a deep breath in, Calla reached up and knocked on the door. A few moments passed and nothing happened so she reached up to knock again, but just as she did, the door swung open and Professor Snape was there, looming in the doorway.
"Enter," he said, blank-faced, though she could tell he was stiff as he stepped back from the door to let her in.
She walked inside his room hesitantly, taking in the shelves full of bottles, the cauldron bubbling in the corner, the ingredients sitting on his desk--and then she jumped as he all but slammed the door shut behind her.
"We will begin now," Professor Snape said, then, without any further explanation, pulling free his wand and stepping closer, but before she could ask for instructions or directions or even a hint, he was saying, "Legimens!"
At once, she felt a presence push into her head, just like the book described, and she struggled to remember what to do next--build a wall around her mind, impenetrable, but every time she tried Professor Snape would crumble it like sand. She could feel him groping around for memories, for visions--and she knew when he found one because she felt a sharp pain and then--
"Ron!" Harry screamed, and Ron turned around just in time to take the troll's club straight to his face.
Blood sprayed across the room, splattering on Calla's face--she could feel the heat of it on her cheeks, wet and sticky--on the walls, the bathroom stalls. There were--chunks. Of strange, meaty gore. Of splintered, red stained bone. Of Ron.
Hermione was screaming at the top of her lungs, shrill, and the troll turned its attention to her next, and Harry was stock-still and pale faced, staring at Ron's body, and Ron--his head was a caved-in mess, unrecognizable--
Calla went to her hands and knees and threw up on the floor of Professor Snape's office. She could feel snot and tears running down her face, and it felt too much like Ron's blood for comfort. She wiped at it with the back of her robes, shaking, and sat back, avoiding Professor Snape's eyes.
"Sorry," she said, even though it really wasn't her fault that he poked her in the brain somewhere nasty.
He just made a disgusted noise and cleared away the vomit with a flick of his wand. "Get up. Again."
This time, Calla used the time she spent standing up to close her eyes and start preparing a wall, building it up brick by brick, imagining sealing all the cracks with mortar. She imagined it stretching up so high she couldn't see the top, so wide that she didn't even know where it started or ended.
Then Professor Snape slammed into it, and it might as well have been made of sticks. With two good hits, it caved in and he was invading another memory, this one--
Uncle Vernon raised his belt and brought it down in rapid succession, over and over again. Each time was met with a crack as the leather met her back, with that awful sort of burning pain that intensified over time.
She was crying, apologizing between sobs, but Uncle Vernon wasn't listening. He never listened. He just hit and hit and hit--
This time, Calla stayed upright, but she did lurch to the side and have to grab onto Professor Snape's desk. She was breathing shakily, and she wiped the back of her hand across her eyes, but after a moment she was able to stand up straight and get ready for another onslaught.
Except, Professor Snape didn't immediately start again. He was too busy staring at her with wide eyes. She opened her mouth to ask him what he wanted, but the sight must've shaken him back into the present because the surprise was all of a sudden gone, and in its place the same bland glare.
Professor Quirrel unwrapped his head, revealing another grotesque face.
Harry and her sat in their closet and played with the few toys they'd snatched from Dudley.
A flash of green, a woman's scream, two children wailing--
"Stop! Stop, please." Calla could hardly catch her breath. Her legs were shaking at this point, her brain aching so much her vision swirled, and--it was so hard. Every time she built a wall, Professor Snape would just blast through it like it was nothing. She was doing something wrong, but she didn't understand what.
"Do you think anyone you go up against will stop because you ask them to?" Professor Snape asked, venomous, the most consecutive words he'd ever said to her, then, "Legimens!"
This time, something in Calla snapped. Fury, hot and righteous, bubbled up, and when she felt Professor Snape prod her mind, she grabbed hold of his presence and yanked, and suddenly--
There was a girl sitting under a tree. She looked just like Calla, but with red hair rather than black. Just like Calla--the same freckles, the same green eyes, the same loose curls.
She was smiling at her--at Professor Snape--laughing and reaching over to poke him, and she--Snape--was laughing, too, something so warm blooming inside her, like nothing she'd ever felt before--
"How dare you!"
Calla blinked, and she was back in Professor Snape's office. He was holding onto his desk with one hand as he glared at her, more rage in his eyes than she'd ever experienced before.
But she didn't care much about that, because, "That was my mom."
"Get out of my office!" Professor Snape snarled.
Calla shook her head, eyebrows coming together, and she looked up at Professor Snape. "You were… friends with my mom?"
"I said, out!"
After a few more moments of watching him, Calla went, but with her she cradled the memory of her mother's young, smiling face and a thousand questions. She’d be back, whether Professor Snape liked it or not.