"Um," said the fairy. "Choose something else."
Rosamund hesitated. It was, she had to admit, the first time she had ever been given a wish, so she wasn't an expert with this sort of thing, but she felt that this was not part of the typical script. "Sorry," she said. "Is that not allowed?"
The fairy grimaced. When it spoke, its voice came out pained and stressed. "Y-y-y-e-e-e-no," it sighed at last, dragonfly wings sagging. "No, technically no, it's not not allowed, but-" It suddenly brightened. "How about gold? Can't go wrong with gold. Gold's a good wish."
Rosamund frowned. This was really not going the way she expected at all. "Excuse me-"
"Beauty, that's a good one too, beauty's always popular," it went on. "And if there's a ball nearby tonight I can probably-"
The wand was twiddled in chitinous fingers. "Right," the fairy said, sounding scolded. "Sorry, it's just..." Its voice trailed off.
Her grandmother's clock chimed midnight from the mantelpiece.
Then - "I'm sorry," it said, not daring to look up, "I know it's not fair, but - you know what I am. You know what we do to wishes. If you wished for wealth I'd have to turn your hair into silver, so you’d have to tear every strand out of your head before you could spend it. We can't help it. It's what we do. The cost of a wish is that you get what you want, but you don't get it the easy way.
"So if you wish for a child, it'll be - strange. Twisted, somehow. Made of pine or marzipan or have the head of a hedgehog. That's the cost of a wish-child; you'll get the child you wished for, but it'll never be - right."
Rosamund waited to see if there was anything else. She felt a sting to her pride when she realized there wasn't. "Is that all?" she said. "I wouldn't care what I got-"
"You all say that," the fairy said. "You all say you wouldn't care what you got. You all say it, and you really believe it, until the neighbours sneer at you and your hedgehog child for too long, or your back aches because your thumb-high child can't help you in the fields, or your pine child kicks and bites and won't obey, and then you think, 'This isn't the way it was supposed to be,' and then..."
The fairy stopped and looked into Rosamund’s eyes. It was a beautiful thing, all glittering carapace and iridescent wings, but just for an instant it looked terribly, terribly old.
"I'm sorry," it said. "But I'm tired of making unloved children."