A great fanfic in this pairing often has a deep understanding of the characters. For example, getting Mytho's complex nature right, his journey from being a broken - hearted prince to finding himself again. And for Princess Tutu, her selfless love and determination. The plot should also be engaging, perhaps exploring their relationship in new and unexpected ways, like how they deal with new threats in the story world that weren't in the original anime.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). There are often a lot of dedicated writers in the Princess Tutu fandom who create great fanfics about Princess Tutu and Mytho. Another place could be Fanfiction.net, though AO3 generally has more diverse and inclusive content. Some Tumblr blogs also reblog and recommend good fanfics in this category.
A possible crossover could involve the villains. The sea witch from The Little Mermaid might be intrigued by Princess Tutu's powers. She could try to steal Tutu's ability to transform things with her dance. This would create a conflict where Tutu has to use her grace and the support of her friends, just like in her own story, to outwit the sea witch.
Redemption is a theme that can be found as well. Characters who have made mistakes in the past strive to make up for it. They try to right their wrongs and become better. This theme gives the characters depth and makes the stories more engaging as we see their growth.
In such a fanfiction, perhaps the duck could be attacked by a dark force while the characters from Princess Tutu are trying to save it. But it gets hurt real bad before they can fully protect it.
The following are some of Hu Tutu's classic sayings:
" In this world, no one can reject the existence of the strong. Only the weak will complain about not having a chance."
2 " The cruelest thing in this world is not war but the human heart."
3 " Nothing is more important than a person's faith, nothing is greater than a person's strength."
" Only the living have the right to pursue their dreams. Only the living have the right to change the world."
Nothing is more important than living, nothing is more precious than living. Only by living can you have a chance to realize your dreams."
6 " Only perseverance can lead to success."
Nothing can stop me from moving forward. Only difficulties and setbacks are my driving force.
"Nothing is more important than your hard work, nothing is more valuable than your persistence. Only by putting in effort can you reap success."
Well, Princess Tutu often has a more European - inspired art style, with elements like castles and ballrooms. The Little Mermaid has a distinct ocean - centered art style. For a blend, the fan - made story could show the mermaid characters adapting to the more terrestrial art style when they come to land. For example, Ariel's hair and tail could take on some of the soft, dreamy colors of Princess Tutu's world while still maintaining her mermaid features. And when Tutu goes underwater, her tutu could start to flow like seaweed and take on a more aquatic look, mixing the two art styles.
Well, here's a story. A group of pirates were sailing the seven seas. Their ship was called The Black Pearl. The captain, Captain Jack, was a cunning man. One day, they heard a rumor about a hidden island full of treasures. They set sail to find this island. Along the way, they had to battle fierce storms and other pirate ships. When they finally reached the island, they found it was full of traps. But they didn't give up. After a lot of exploring and solving puzzles, they found the treasure. It was a chest full of gold and jewels.
One story could be about how Desmond Tutu inspired children through his message of love and equality. For example, he might have visited a school in South Africa. The children there were facing discrimination at that time. Tutu told them that every person, regardless of skin color, is equal in the eyes of God. His kind words and warm smile gave the children hope and the strength to believe in a better future, where they could all live together without prejudice.