Yes, there are likely many. You can start by looking on popular fanfic platforms like Archive of Our Own. There are often stories that explore Eugene's love for Rapunzel in great detail, showing different scenarios and character developments within the Tangled universe.
In these fanfictions, Eugene as the Dark Prince might have new powers. For example, he could have some shadow - based abilities. The story could be about his struggle to control these powers while also dealing with the expectations of others. Maybe he has to face an enemy that only his new form can defeat, but at a cost to his own humanity.
Eugene could be telling Rapunzel a story about his childhood while she leans on his shoulder. Rapunzel might also sing a soft lullaby she learned in the tower, and Eugene would listen with a smile on his face. Then they would slowly fall asleep, with the gentle breeze blowing through Rapunzel's long hair.
Once upon a time, in a far - away land, there was a beautiful girl named Rapunzel. She had long, magical hair. Eugene, a charming and roguish young man, stumbled upon Rapunzel's tower. Rapunzel was curious about the outside world, and Eugene promised to show it to her. They went on an adventure together, facing many challenges. At bedtime, they would find a cozy place in the forest. Rapunzel would use her hair as a blanket, and Eugene would tell her stories of his travels. And they would fall asleep under the twinkling stars.
In the world of Tangled Rapunzel and Eugene fanfiction, 'EnchantedQuill' is a top author. Their writing style is very descriptive, making you feel like you're right there with Rapunzel and Eugene. 'RoyalRomanceWriter' is also excellent. They often explore different aspects of Rapunzel and Eugene's life after the events of the movie, such as ruling the kingdom together and dealing with new challenges that come their way.
One sign could be that he starts to think about her all the time. Even when they're apart, she's constantly on his mind. He might find himself daydreaming about their conversations or the times they've spent together.
One possible plot could be that Eugene and Rapunzel are overjoyed at the news of expecting a baby. They start preparing the castle for the new arrival. Rapunzel might paint the nursery with beautiful murals inspired by her past adventures. Eugene, on the other hand, could be seen training the guards to ensure the safety of the future heir. There could also be some challenges like Rapunzel having cravings for rare ingredients which sends Eugene on a quest to find them. And they would have to deal with the expectations of the kingdom as well.
One plot idea could be that Eugene has to go on a dangerous quest alone to find a magical herb to cure Rapunzel when she falls ill with a strange disease that normal medicine can't heal. Another could be a story where Rapunzel and Eugene accidentally swap bodies due to a magical mishap and they have to figure out how to reverse it while also dealing with the daily tasks in each other's bodies.
In some fanfics, it might be during a dangerous situation. For example, Rapunzel could be in danger from some bad guys, and Eugene feels a sudden rush of protectiveness. He realizes that he doesn't just want to protect her because it's the right thing to do, but because he loves her deeply. He can't bear the thought of losing her, and that's when it hits him.
One plotline could be Eugene being forced into becoming the Dark Prince against his will. Maybe by some dark magic or an evil entity. And then the story could be about him trying to break free from this dark influence.