One possible storyline could be that Harry leaves to explore the wizarding world outside of Britain. He might go on a journey to discover new magical creatures and spells in far - off lands. Another could be that he leaves to find a place of peace and solitude, perhaps in a hidden magical enclave, to deal with the trauma of the war. And he could also leave to train young wizards in secret, away from the public eye, to ensure they are well - prepared for any future threats.
In some fanfictions, Harry leaves to start a family away from the spotlight. He wants his children to grow up without the burden of his fame. He might choose a small cottage in the countryside where he can teach his kids magic in a more natural and less pressured way. Another idea is that he leaves to join a group of magical nomads. These nomads travel from place to place, sharing and learning different kinds of magic. Harry could see this as a way to expand his understanding of magic and also contribute his own knowledge.
Maybe Harry leaves to start a new life as a healer in a remote wizarding village. He uses his experiences from the war to help those with both physical and mental wounds. Or he could leave to study ancient magic more deeply. He might feel that there is so much more to learn about magic that was lost during the war and goes off to search for answers in old libraries and with wise old wizards. Also, he could leave to find a way to break the cycle of dark wizards rising, by traveling and researching dark magic to find ways to counter it.
One possible storyline could be that Harry leaves to explore the wizarding world outside of Britain. He might go on a journey to discover new magical creatures and spells that were previously unknown to him. Maybe he wants to find a place where he can truly be at peace after all the chaos of the war.
One possible storyline could be them rebuilding the wizarding world together. They might focus on restoring Hogwarts, with Ginny using her Quidditch skills to start a new team there and Harry helping with the overall magical education revival. Harry could also be involved in Auror training reform, and Ginny would support him through it all, and they'd start a family in the newly peaceful wizarding world.
One possible storyline could be Harry struggling with PTSD from the war. He might isolate himself in Grimmauld Place, haunted by the memories of those he lost. Another could be him trying to find a new purpose in life, perhaps traveling the wizarding world alone to discover forgotten magic. Or he could be dealing with the public's perception of him as the 'Chosen One' and feeling the pressure to always be strong and heroic.
Maybe some of the old grudges between wizarding families that were thought to be resolved start to flare up again. This could lead to a lot of political intrigue within the wizarding community. And the children of the main characters could get caught up in this web of family feuds, having to decide whether to follow their family's old ways or try to make peace.
In this fanfiction, Harry could be alone because he feels estranged from his friends who have moved on with their lives in different ways. So he takes on a solitary mission to protect the wizarding world in the shadows. He becomes a sort of unseen guardian, constantly thwarting small threats that could potentially grow into big problems, all while dealing with his own loneliness and the memories of the war.
Perhaps Harry meets magical creatures that are rarely seen by wizards. Since he is out exploring after the war, he might stumble upon a group of centaurs who have their own unique wisdom about magic and the future. He could also encounter veelas, and through his interactions with them, learn more about the different cultures within the magical world. There's also a chance he meets other young wizards who are on their own adventures, and they form a sort of traveling group together.
One possible storyline could be Harry's struggle with his newfound loneliness and how it affects his magic. He might start to isolate himself more from his friends at Hogwarts, fearing that he'll lose them too. Another could be Harry's determination to avenge Sirius by seeking out the Death Eaters responsible for his death more aggressively.
One interesting storyline could be how the wizarding world rebuilds. For example, Hogwarts might need a lot of repairs after the war. The characters could be involved in restoring the castle, classrooms, and magical artifacts.
One possible plotline could be that some of the former Death Eaters who were pardoned as part of the post - war reconciliation secretly plot against Harry. They might spread false rumors about him misusing his power or being a threat to the wizarding world again. Another could be that some of his own friends turn on him out of jealousy. Maybe they feel overshadowed by Harry's continued fame and hero status and start to believe the lies being spread about him.
One possible storyline could be Harry's struggle to prove his innocence while in Azkaban. Maybe he discovers some dark secrets within the prison walls that are related to a larger threat to the wizarding world. Another could be his attempts to escape and the friends he makes or enemies he encounters during the process.