Well, perhaps the ritual is related to enhancing their magical abilities. Harry might be providing moral support and practical help like gathering rare ingredients for Hermione. Maybe they need to perform the ritual to protect Hogwarts from a new dark threat.
It could be the Death Eaters. They might not want Harry and Hermione to succeed in the ritual as it could be a threat to their dark plans. Or maybe some other dark wizards who are envious of the power that the ritual might bestow on Harry and Hermione.
In this fanfic, a student at Hogwarts might be bullied because of their parents' status. They come across a magical ritual that is said to be able to change the very essence of a person. They decide to use it on their parents to make them more respected in the wizarding community. The ritual requires the use of a powerful magical crystal, a potion made from a basilisk's fang, and a spell spoken during a lunar eclipse. However, when they perform the ritual, it causes a rift in the fabric of magic. Dark forces start to seep into the wizarding world, and the student realizes they must fix the ritual's effects before it's too late. They embark on a journey to find ancient spells and magical beings that can help them reverse the damage and also learn a great deal about the true nature of magic in the process.
In a fanfiction, perhaps Lucius Malfoy has lost his wealth and status due to Voldemort's fall. Hermione, being the kind - hearted person she is, decides to help him get back on his feet. She might use her skills in magic and her connections in the wizarding world. Maybe she helps him find a job at the Ministry of Magic in a department that could use his knowledge of the old pure - blood families' ways. This would be a very different Lucius, humbled by his circumstances, and Hermione's help could lead to a character - growth arc for both of them.
Maybe Hermione has lost her confidence in her magical abilities due to some traumatic event. Snape, in his own gruff way, decides to mentor her. He helps her recover by guiding her through difficult spells and magical concepts she had previously mastered but forgotten. This journey of recovery could also involve them exploring parts of Hogwarts that are little - known, and in the process, they form an unlikely friendship.
One possible plot could be that Hermione and Harry discover a magical cat that has the ability to communicate with them. This cat leads them on an adventure to find a hidden magical artifact. Along the way, they use their knowledge and skills to overcome obstacles.
One possible plot could be that Harry and Hermione somehow end up in Westeros through a magical portal. They might use their magic skills from the wizarding world to deal with the political intrigue in Westeros. For example, they could help a certain house in the Game of Thrones - like scenario, using spells to protect their allies or uncover the secrets of their enemies.
One possibility could be that Harry and Hermione start a magical research project together. They explore some long - forgotten spells and their implications in the wizarding world. Maybe they discover a new way to use magic that could change the way magic is taught at Hogwarts.
It could be that the goblins are facing a threat from dark wizards, and Harry steps in to help. He might teach them some defensive magic techniques that humans use, and together they form a plan to fight off the dark wizards. Harry's fame and experience could give the goblins the confidence they need to face their enemies.
One possible plot for this fanfiction is that Hermione wants revenge on the Death Eaters who have caused harm to her friends and the wizarding world in general. Dolohov, having once been a Death Eater himself, could provide crucial information about their hideouts, plans, and weaknesses. This would give Hermione an edge in her quest for revenge. He could also use his combat skills, which are no doubt formidable, to protect Hermione during her confrontations with the bad guys.
One possible plot could be that Hermione discovers a Death Eater who has doubts about Voldemort's cause. Maybe the Death Eater has a family member who was unjustly punished by Voldemort. Hermione, being the intelligent and empathetic witch she is, offers the Death Eater a way out. She could provide a safe haven or help them fake their death and start a new life away from the Dark Lord's influence.