The Doll.
It didn't matter to her that The Doll was broken, one of its arms ripped off, its hair tangled and its clothes dirty and torn. It didn't matter to her, because The Doll was hers.
She'd kept The Doll with her for years now, she was going to boarding school now, leaving everything behind, but she had managed to fit The Doll into her bag. The Doll was the same as it always had been, still broken, one of its eyes was missing now, but it was still hers. The first thing she had.
She took it with her every year to boarding school, even though she was 15 now, and she was supposed to be a little lady, who thought that everyone was beneath her, and she was. Just not when she was alone with The Doll, because The Doll was her best friend, it had been there when she moved to the orphanage, when she was sent back there, again, and again, and again, because she refused to do what the Others wanted her to do.
No-one else knew about The Doll, it was well hidden, under the false floor of her suitcase at school, and under her pillow at the orphanage. So no-one knew that the little 'ice queen' told a broken doll everything that had happened that day in whispered tones every night before she fell asleep.
Until one day, when the girl forgot to put away The Doll in the morning before the Other People in the dormitory at school woke up. They saw The Doll and laughed, they stole The Doll from her and ran away, still laughing, and when the girl chased them, the Other People laughed even harder and burnt The Doll in front of the whole school.
That is why the girl hasn't spoken in 15 years; she has no-one to speak to. But that's fine, because no-one remembers the girl, or The Doll. No-one remembers because no-one saw her before, and no-one saw her afterwards. But you must have, if you're asking about her, or do you remember The Doll? She won't mind either way, if you talks to her voluntarily, you'll probably have just made her life worth living.
She's just up this corridor, dear, what did you say your name was?
Ahh yes, she remembers you, weren't you one of the ones who was in the background as well? Mentioned in the sorting, and then almost forgotten... yes...that happened to her as well.
I do feel sorry for her, the poor dear, it's such a shame what happened to her, that Sally-Anne Perks used to be such a lively child.