One possible plot could be that they sing to cheer up their friends at Hogwarts during a difficult time, like after a battle or when everyone is feeling down because of exams. Their singing could have some magical effect that lifts the spirits of those around them.
Yes, there might be some. Fanfiction websites like Archive of Our Own (AO3) or FanFiction.net could potentially have such stories where Harry and Hermione sing. You can search for relevant tags like 'Harry Potter', 'Harry', 'Hermione' and'singing' on these platforms to find them.
Maybe Harry and Hermione have a misunderstanding at the very beginning, like a fight over a Quidditch match result that gets out of hand. So they decide to not be friends. Then, Hermione might form an alliance with Draco out of spite towards Harry, and Harry could find himself more alone and start to rely more on Neville. This could lead to a whole new set of adventures and challenges in Hogwarts.
One possible plot could be that Harry and Hermione find an orphaned baby during their post - Hogwarts adventures. They decide to take the baby in and raise it as their own. Along the way, they face challenges like protecting the baby from dark forces that might be interested in the child's potential magic. They also have to balance their own relationship and the new addition to their family life.
Well, perhaps in the fanfiction, Harry and Hermione find a child who has special needs in terms of magic. For example, the child has an uncontrollable magical power that scares other families away. But Harry and Hermione see the potential in the child. They start to work together, with Hermione using her vast knowledge of magic and Harry using his own experiences, to help the child learn to control their power. As they do this, they form a very close family unit.
Perhaps the story could revolve around them facing challenges within the Hogwarts faculty. There could be some old - fashioned professors who oppose their modern teaching methods. Harry and Hermione then have to prove that their ways are beneficial for the students. They might also discover new magical abilities in some of the students that were previously overlooked, and help those students develop their skills.
One possible plot could be that while they are on the run and hiding in the tent, they find unexpected love and a sense of family. Maybe they are forced to rely on each other more than ever, and this closeness leads to a romantic relationship and then the pregnancy. It could be about how they deal with this new situation in the midst of danger and their quest to defeat the Dark forces.
Well, it could be a comical plot where Harry, for some magical reason, is turned into a small animal and Hermione takes him in as a pet. Maybe he still has his human mind and has to communicate in funny ways to Hermione, leading to all sorts of hilarious misunderstandings and adventures.
In the fanfiction, Luna might be lost in a time - loop created by a malfunctioning time - turner. Hermione realizes what has happened due to her familiarity with time - turner magic. Harry goes with her to enter the time - loop. Inside, they face various challenges from different time periods. They find Luna, who has been trying to break the loop on her own. The three of them then work together. Hermione figures out the correct sequence of spells, Harry provides the necessary distraction to the time - loop's guardians, and Luna uses her natural connection to magic to help Hermione complete the spell that breaks the loop.
Perhaps in the fanfiction, Harry and Hermione raise a child who has a connection to a long - forgotten dark magic. They have to protect the child from those who would use the child's power for evil. Along the way, they face challenges in the wizarding world where some people are suspicious of their decision to raise this special child. But they stand strong, using their combined knowledge and skills to keep the child safe and raise it with good values.
One possible plot could be that they are in a magical pool area. Hermione has a special bikini that has some magical properties. When Harry sees her in it, he is intrigued. As the story progresses, they might get involved in some sort of magical adventure related to the bikini, like it being a key to an underwater magical realm. Along the way, their relationship could develop further, whether it be a stronger friendship or the start of a romantic relationship.