The following Monday....
Arcturus was roused early that morning by Remus' reserved tones, as he had been every morning for the past week. Arcturus had been interacting with the dark haired girl who helped him as much as he could, but she was rather good at avoiding other people.
Breakfast was a blur, in fact most of the day was too. It was their final lesson for the day, charms, that was the most interesting. They were learning the colour change charm. The instruction was to read page 149 of their textbooks, and then attempt the incantation on the white wooden blocks that the charms professor had given them. The book read:

"Colovaria (co-lo-VA-ree-ah)
The colour change charm is a charm which causes an object or animal to change its colour."

Arcturus held his wand carefully in his fist, pointing it at the block.
"Colovaria." He muttered. The white block immediately turned a vivid sky blue. Arcturus smiled. "Colovaria." He uttered again, and it changed to acid green. Sirius was also having no trouble. His block was changing colour every second, Sirius muttering constantly under his breath. Arcturus glanced around the room, noticing that some kids had managed it well, while others had failed to make their block change all the way, having a half white, half coloured block and a frustrated expression on their face, and still others had a white block.
He did a double take as he noticed the mysterious girl, Hart. Her block was an extremely bright pink, and he noticed that tendrils of colour had crept across the desktop like pink lightning bolts. That must have been a strong charm. As he watched, she was twirling her wand between the fingers of her right hand absent mindedly. A lock of her hair touched against the tip of her wand, and her whole head of black hair turned a dark blue colour, as did the uncoloured parts of her desk and parts of the floor around her. She looked shocked and dropped her wand, which went off like a gun and changed the blackboard into a fat pink piglet. She blushed furiously, snatched her wand from the ground and scampered out of the classroom to the disappointed mutterings of the professor, and the dark, teasing clamour of the other students. Arcturus gripped his wand and ran out the door after her. As he stepped out, he spotted a last trail of dark blue hair flash around the corner, and dashed towards her.
"Hey! Wait up!" He called out. She skidded to a stop and slowly turned around.
Her blue eyes appeared glassy, as though she was about to cry.
"What?" She sobbed, and a tear rolled down her cheek.
"Hey, don't cry!" He said soothingly. "I'm not here to bully you. I'm genuinely concerned." He told her. She glanced up at him, appearing almost disbelieving.
"Really." He gave her what he hoped was a reassuring smile. "Is your hair okay?" He questioned.
"I dunno. I can't reverse it. I just tried." She sounded deeply sad. Arcturus lifted his wand, and she flinched. He said
"Colovaria." And her hair turned from the dark blue to her natural black. Her eyes widened. "I know how embarrassing it can be for your hair to be tampered with." He smiled, thinking back to his horror at the Black reunion.
"Thankyou." She sounded taken aback, and happier.
"Don't thank me, i owed you." He said. She took two cautious steps in his direction.
"For what?"
"You helped me when i was lost.... So i helped you when you felt the same." Arcturus responded. She crept another few steps forward. Arcturus could smell her perfume faintly from her new proximity.
"Thank you. What's your name?" She met his gaze.
"I'm Arcturus Black." He smiled back, "and you?"
"Cassandra Hart." She reached out, pressed her palm against his upper arm, and gave him a faint smile before she briskly made her escape down the corridor.
"Cassandra." He whispered, holding the spot where her palm had rested on his arm and smiling after her.
Arcturus then turned away and headed back towards the classroom with a spring in his step. Remus and Sirius almost ran into him at the door.
"Where did you go?!" Sirius chided.
"It had better not be that Hart girl." Remus warned.
"I- uh- i needed the bathroom." Arcturus didn't like lying, but if they knew the truth, they might try to stop him speaking to her.
"You're a terrible liar, Arcturus." Sirius smirked,
"I couldn't agree more. Look, that Hart girl is bad news. It's probably not her fault, but even if the curse doesn't exist, she at least doesn't have very good control of her magic, and she happens to be quite clumsy. She could seriously hurt you." Remus explained carefully. "Why don't you try dating a different girl or something? It would be better for you, and it would do Hart good too. She's had alot more unwanted attention from jealous fourteen and fifteen year olds since you took an interest in her. Just the other day she got into a wizard duel with another girl. Supposedly she said something rude about her, but Sirius' on again-off again- broom closet companion let slip to him that the girl had been after you since she first saw you, and that the fact Hart gets so much attention off of you made her quite jealous." Remus frowned slightly.
"Cassandra avoids me constantly." He said,
"Yes, but rumour spreads fast around here, and everyone knows that you've been asking after her." Remus glanced in his direction.
"Okay.... I still want to get to know her, and isn't that kind of up to me?" Arcturus questioned.
"True, but i really think you should just get to know a different girl. Just try it! Who knows, you might just like it." Remus shrugged. "Now i've got study to do. I'll see you later." He reasoned, and then he turned around and stalked off.
Arcturus watched him leave, and as he did so, he thought about what his friend had said. Maybe he should just find another girl. Maybe it was actually not such a bad idea. Maybe Remus was right, and Cassandra Hart really was bad news. Arcuturus understood now. Hart was gorgeous, but she was a liability. He should just let her go.