Soulmates

Devyn Creevey was known for her mischief, she had come to Hogwarts at age 11, and had been sorted into Hufflepuff, though many of the other houses felt she belonged in Slytherin, and even Dumbledore, had stated they sort students too soon, and she should have been a Slytherin. Devyn was muggle born, and both her elder brother Dennis, and younger brother Colin, showed signs of being wizards, Dennis had been sorted into Gryffindor, two years prior to Devyn becoming of age, and everyone expected her to follow in his shoes. The day she was sorted, all that could be heard was gasps from other houses, shocked, even her brother Dennis was confused.
Devyn had not held up the Hufflepuff image through her first few years, and had nearly been expelled several occasions, although Professor Snape had managed to keep her in school by defending her, she was his favorite student. Other professors also defended her, she was the top of her classes, and no doubt she'd become Head Girl. Her parents were few of the muggles who knew of the wizarding world and were immensely proud of both her and Dennis.
She had befriended Fred and George Weasley in first year, they were all the same age and they also liked mischief as much as she did, she had even helped them steal a map from Filch's office, and helped them figure out how to view it, along with their friend Lee Jordan, they used the map often to get around without being seen. The four of them were as close as anyone could possibly be, they were the modern-day Marauders.
She was in her sixth year when the writing started to appear on her arm, her soulmate... she had not even realized she'd become of age, But there was the simple word. Hello.. She had no idea how to respond but her fingers traced over the word again and again, when she'd finally decided to write a hello back, the word disappeared, and hers stayed until her soulmate replied.
What happens when your soulmate, or should I say soulmates end up being your best friends?