The young man who sits at the edge of the pier was a knight once. Now he is a writer. One would expect him to write tales of glory: the sort of thing a knight would have lived through and experienced, just as he did. He could write about the fight to defeat the evil Raven, or how the prince was rescued and then rescued his true love. He has lived through it, this quiet writer on the edge of the pier, and he could write about it if he wants.
But there is someone else who has lived through it next to him in the water. She was a princess once, and she was a girl once, and she was always a duck. Now she is a duck again. It would be silly for the young man who sits at the edge of the pier to write tales of glory, because on these special days when he sits at the edge of the pier, he writes for her, and the two of them have lived through all that. They wore the mask of the knight and the mask of the princess for long enough. Now they are a writer and a duck, which is what they always were, even if it took the writer some time to learn about it.
So he does not write tales of glory. He writes, instead, of all the ordinary things he has seen. He writes about two loud and passionate young girls arguing over who likes whom and scheming to reveal it. He writes about a cat who searched long and hard to find a lady cat who would love him, then discovered her and started a family. He writes about dancers. When he writes about the prince and his true love, he writes about their simplest happy moments, not any adventures they might have.
Something strange happens as he writes. After a little while, the duck climbs out of the water. She does not turn back into a girl or a princess; she is simply a duck out of the water. But she knows exactly where to go. She settles down on the writer's shoulder, leaving wet webbed footprints on his shirt, then clambers down his arm to watch him write. He does not shake her off, even though it must be difficult to write with a duck on his arm. Instead, he continues to write patiently until he is done with his story. Then he turns the book to show it to the duck, and his serious expression melts into a smile.
Then the duck reads. She reads the whole story, whatever it is, no matter how plain and ordinary the things it describes are. When she is done, she quacks to let him know. It is a satisfied quack. The writer can tell things like that. The duck is surprisingly expressive with her vocabulary of quacks and earnest gazes. They smile at each other. You should not ask how a man and a duck can smile at each other. For these two, you should only know that it is not only possible, it is easy.
When all that is done, the duck climbs back into the water, far more clumsily than the princess used to dance, but also far more naturally. The young man might return to his writing, or he might simply sit there at the edge of the pier and watch the duck as she floats in the water. Whatever he and the duck do, it is entirely up to them.