Another plotline might be that Guren goes missing. Yuu then embarks on a journey to find him. Along the way, he meets people who knew Guren in the past and through their stories, Yuu gets to know a different side of Guren. When he finally finds Guren, their relationship is transformed.
One way it can explore their complex relationship is through flashbacks. Maybe show Yuu's early memories of Guren, like how Guren's actions made Yuu feel both admiration and confusion. For example, Guren's strict training methods could be seen as tough love from Yuu's perspective as he grows older.
One possible plotline could be about Guren and Naruto having to protect their unborn child from enemies who might see it as a threat. Since Naruto is a powerful ninja and Guren has her own abilities, they would have to use their skills to keep the baby safe. Another could be them preparing for the baby's arrival, like finding a safe place to live and getting support from their friends.
In certain fanfiction, a plotline could involve Naruto being injured and Guren taking care of him. As she nurses him back to health, they have long conversations about their views on the ninja world. This interaction makes them realize how similar they are in some ways, and it could be the start of a unique relationship between them. This relationship might then face challenges from their respective villages or from other ninja who don't approve of their alliance.
One possible plotline could be Damon gradually finding the strength to stand up to his father. Maybe he starts by confiding in a close friend, who then helps him gather evidence of the abuse to take to the authorities.
A plotline could involve Percy using his powers, which he may have inherited from Erebus, to fight against some great evil. Maybe there's a force threatening the world that only Percy, with his unique abilities, can stop. He could also be on a journey to discover more about his father and his own place in the world of the fanfiction.
One possible plotline could be Yuu struggling with his new vampire nature while still trying to protect his friends. He might have to deal with the thirst for blood and resist the urge to harm his comrades. Another could be that he uses his new vampire abilities to fight against the real enemies of the series in a more powerful way. For example, he could use enhanced speed and strength to take on the vampires that are causing chaos in the world of Owari no Seraph.
In this fanfiction, a plotline could involve Percy having to introduce Annabeth to his side of the family. This would be really interesting as it would show a whole new aspect of Percy's world to Annabeth. Another plotline could be Annabeth getting into trouble at school or with other demigods, and Percy having to step in as her father to resolve the situation. This would show how he uses his influence and authority in this new role. There could also be a plotline where Percy and Annabeth find out that there's a prophecy related to their new relationship. They would then have to figure out what it means and how to fulfill or avoid it, which would add a lot of tension and mystery to the story.
One possible plotline could be Harry struggling to balance his new role as a father with his studies at Hogwarts. He might face challenges from the school authorities who are not used to a teenage student being a father.
One possible plotline could be that Adrien's father is facing a financial crisis, and Adrien uses his intelligence and charm to attract investors or find new business opportunities. Another could be that his father is ill, and Adrien takes on more responsibilities at home and in his father's business to keep things running smoothly.
One possible plotline could be Draco finding out about his true parentage and having to keep it a secret from the Death Eaters who expect him to follow in Lucius' footsteps. He might start to question his loyalties and gradually side with the Order of the Phoenix.