Now, Ahiru is the Japanese word for 'duck', which makes perfect sense considering she's a duck who was magically transformed to a human girl. The English dub chaned this, reasonably enough, to 'Duck'. However, 'Duck' just doesn't sound like a human name - a joking nickname at best. It's one of those Inherently Funny Words, and I am reluctant to use it. However, I am equally reluctant to use a Japanese word when the anime is not set in Japan.
So where is it set? Well, one shot of Fakir writing sugest he's writing in German. It makes as much sense as anything; 'Drosselmeyer' sounds like a German name.
The German word for 'duck' is 'Ente'. It's fairly easy to imagine 'Ente' as someone's name, and if the 'story' was being told in German, that's what Ahiru would have been called, right? The only problem with this is that if I use it in a fic, no one will have the faintest idea what I'm talking about.
... I hate it when that happens.
By June Fakir began to worry. Seeing Ente's yellow plumage falling away left him writing half the night. By mid-July Ente was white-feathered and full-grown, and he was frantic.
By September he was crying into his inkwell. Ente perched on his bed, looking at him sadly. "I don't know what to do," he told her, wiped his eyes and picked up his pen. When he finished the paragraph he looked back.
Sitting on his bed was a red-haired woman. She looked sixteen, not the ten he had known. "It's alright," she said, and held out her hand. "You did it anyway."