One plotline could be that Harry discovers a hidden diary of Kitiara's and it reveals secrets that set him on a quest to protect her legacy.
Perhaps there's a plotline where Harry has a vision of Kitiara in trouble in a parallel dimension. He then has to find a way to cross over and save her, facing all kinds of magical and non - magical obstacles along the way.
One possible plotline could be that Harry Potter decides to take on the Dark Arts in a more proactive way. Instead of just reacting to Voldemort's attacks, he studies the Dark Arts himself to find weaknesses, which is a very bold move for him considering the taboo nature of the Dark Arts in the wizarding world.
One plotline could be that a young wizard finds the ashes of a phoenix and they start to have strange dreams. The dreams lead him to discover an ancient magic that was thought to be lost. Another could be that a group of Death Eaters try to steal the ashes to use in a ritual to bring back Voldemort in a more powerful form.
Sure. One example could be a plotline where Harry discovers he's actually an alien from another dimension and his magic comes from that origin rather than his wizarding heritage. Another could be a story where all the Hogwarts houses merge into one super - house and there are no more rivalries or differences between the students. And there might be a plot where the Marauder's Map actually turns into a living being that can guide Harry on adventures that have nothing to do with Hogwarts or the wizarding world as we know it.
One plotline could be Naruto being the only one who can tame the Juubi. So, he has to go on a journey to master the Juubi's power and use it for good. Another could be that the Juubi is somehow split into different parts, and Naruto has to find all the parts to prevent an evil force from using it to destroy the world.
One plotline could be that Hogwarts is under a new curse that makes the castle itself a dangerous place. The staircases are constantly shifting in a more erratic way, and there are hidden traps everywhere. The characters have to navigate this while also dealing with a new group of dark wizards who have infiltrated the school.
One plotline could be that Richonne discovers their baby is allergic to a certain type of baby formula. So they start a journey to find a suitable alternative, meeting various characters along the way who either help or hinder them in their search.
A possible plotline is that there is a hidden village in the Naruto world that is built around the worship and use of dragon lacrima. The main characters, like Sasuke and Naruto, are invited to this village for a tournament. During the tournament, they discover a conspiracy involving the misuse of dragon lacrima that could endanger the entire Naruto world.
One plotline could be that a young wolf in the pack discovers a lemon tree and the lemons have the power to give the wolves the ability to communicate with other animals. So, the pack has to protect this lemon tree from other predators who want to use the lemons for their own gain.
Sure. One plotline could be a young orphan on an island is 'adopted by default' when a passing pirate crew decides to take them in after seeing their potential. The orphan then has to learn the ways of the pirates and deal with the crew's various personalities.
One plotline could be that Draco tries to find the source of the curse himself. He embarks on a journey, facing various obstacles and meeting different characters along the way who either help or hinder his progress.