Another theme is the relationship's impact on the wizarding world. In some stories, Harry's relationship causes a stir among the pure - blood families or changes the power dynamics at Hogwarts. It can also lead to new alliances or enmities. A good example is when his relationship might influence the way the Order of the Phoenix operates.
One common theme is the exploration of forbidden love. For example, when a character from a different house or with a different social status in the wizarding world falls for Harry. Another theme is the growth of the relationship through shared adventures, like fighting dark wizards together.
One common theme is secrecy. Harry has to keep his wizarding life a secret from his Muggle girlfriend, which often leads to tension. For example, in many fanfictions, he has to make excuses for strange happenings around him.
One common theme is the clash of cultures. The Muggle world and the wizarding world have very different norms and values, and this often creates interesting situations in the fanfics. For example, how a Muggle girl reacts to magic or how she fits into the wizarding society.
The theme of identity also comes up. Harry is known as 'The Boy Who Lived' and a great wizard, but with cancer, he becomes just another person facing a life - threatening disease. This makes him re - evaluate who he is and what his purpose is. It also shows how the wizarding world reacts to him when he's not in his full - strength heroic state.
One common theme is the struggle with magic. Since magic can be unpredictable, it can be a source of stress for a Harry with OCD who likes order. Another theme could be his relationships, like how his friends react to his OCD - some might be supportive, others might be confused at first.
One common theme is identity. When Harry has amnesia, he has to rediscover who he is. Another theme is friendship. His friends play a crucial role in trying to bring his memories back. For example, they might use the Pensieve to show him his past experiences.
It could be a Muggle - born witch who he meets outside of Hogwarts during the summer holidays. She's not part of the typical wizarding society he's used to, so they keep it a secret as it's an unusual situation for a wizard like Harry to be involved with a Muggle - born in such a way.
One common theme is destiny. It often shows that Harry and his soul mate are meant to be together by some greater force. Another theme is self - discovery. Through the relationship with their soul mate, Harry or the other character discovers more about themselves.
Identity is a big theme as well. The new - found sibling might struggle with their identity as a Potter. Are they going to be in the spotlight like Harry? Or will they try to carve out their own path? This exploration of identity can be really engaging in these fanfictions. Also, the theme of loyalty comes up. Will the sibling be loyal to Harry and his cause against Voldemort? Or will they be swayed by other forces? These are all aspects that are commonly explored in 'Harry Potter has a sibling' fanfiction.
One common theme could be the exploration of different relationships Harry Potter has with multiple characters in the harem. It might show how he manages to balance his feelings and interactions with them all. Another theme could be the development of unique storylines around the group dynamics within the harem, like how they support or compete with each other in relation to Harry.