The ghost children have been trapped by the other mother for a very long time. So long, in fact, that they dress and speak in an old-fashioned way. But what purpose do the children serve in the story? Coraline already had to save her parents; why add the children's souls to the mix? Well, there are a lot of ways to answer that, but we think of these three kids as a stinging reminder that Coraline doesn't really have any friends in her real world. (Hopefully, though, things will change this school year.)
The ghost boy is the most outspoken of the three ghost children. He's the one who gives us the scoop on the ghost kids and how they ended up stuck in the other mother's world. Once upon a time, the little ghost boy was a curious and happy kid, until he got trapped in the other world.
"I found myself back in the parlor. But she was waiting for me. She told me she was my other mamma, but I never saw my true mamma again." (7.26)
It all ends up okay, though: when Coraline meets the little boy in her dream after she rescues him, he's definitely a lot of fun.
The ghost girl that Coraline rescues is much more reserved, or quiet, than her counterpart, the ghost boy. She's dressed very conservatively and she sounds older than the little boy. Even when we meet her at the picnic in Coraline's dream, she's pretty serious:
She was wearing a rather shapeless brown dress, and had a brown bonnet on her head which tied beneath her chin. "And we are more grateful for it and for all than ever words can say." (12.24)
Now that we've met the boy and the girl, here's some food for thought: if you combine the personalities of the boy and the girl – outspoken and fun vs. mature and serious – you kind of get, well, Coraline. When you add the fact that these children live in the mirror, it begs the question: are these kids just a reflection of Coraline herself?
At first, we think there are two little girls stuck in the mirror. But when Coraline dreams of the three children, she discovers something surprising.
Coraline could have sworn the girl had two wings – like dusty silver butterfly wings, not bird wings – coming out of her back. [....] She smiled at Coraline, as if it had been a very long time since she had smiled and she had almost, but not quite, forgotten how. Coraline found herself liking this girl immensely. (12.25)
Could it be that this other girl is really a fairy? Fairy or not, this girl has a lot of personality: out of all the children, Coraline likes her the best. Unfortunately, all three of these children passed away a long time ago. But Coraline has the memory of these would-be friends, and she thinks of them fondly in the last scenes of the book. The memories are invaluable; as the children themselves say, "[w]e keep our memories longer than our names" (7.12).