One challenge would be the goblins. They are very protective of Gringotts and would not easily give up control. They have their own laws and traditions regarding ownership. Harry would have to deal with their resistance and find a way to convince them or negotiate with them.
Managing the bureaucracy within the Ministry is no easy feat. There are likely many long - established traditions and procedures that might be resistant to change. Harry, who might be more used to action - oriented tasks, will have to learn how to deal with the red tape and inefficiency that often comes with a large organization like the Ministry.
He'd face opposition from the wizarding community. They might not understand his choice to leave behind the world of magic for a religious life. His friends like Hermione and Ron would also be confused and try to talk him out of it.
One challenge could be controlling his new powers. Deadpool's powers are quite wild, and Harry, used to more traditional magic, might struggle to master them. Another challenge could be how the wizarding world views him. His new powers and the resulting change in his behavior might make him an outcast among some in the wizarding community.
One challenge could be dealing with the traditional teaching structure at Hogwarts. The school had a set way of doing things, and Harry, with his more hands - on and unorthodox approach, might face resistance from some of the more conservative teachers. For example, they might not approve of his idea of using real - life dangerous situations as teaching examples.
There could be a fanfiction where Harry Potter's Animagus form is a phoenix. When approaching Cerberus, the phoenix's natural magic and allure might have an unexpected effect on the fearsome beast. The phoenix is a symbol of rebirth and magic, and perhaps its presence could either calm Cerberus or lead to a completely different kind of encounter. Harry would have to rely on his instincts as a phoenix - Animagus to navigate this dangerous situation, and it would be a great adventure for him.
There is a vast amount of Harry Potter fanfic out there, but 'face sitting' often implies inappropriate or adult - themed content. In the world of Harry Potter fanfiction that adheres to family - friendly and canon - respecting rules, such a concept is not likely to be part of it. The official Harry Potter universe focuses on magic, friendship, and the battle between good and evil, not on such improper concepts.
Another challenge would be handling the different houses. Each house has its own identity and sometimes rivalries can get out of hand. A new headmaster would need to find ways to promote unity among the houses, like through new inter - house competitions or joint projects.
One challenge could be the conflict between the rules of magic he already knows and the new principles of the Force. For example, the way spells are cast in magic is very different from how one might use the Force, so he has to unlearn some habits. Another could be the opposition from some of the more traditional Hogwarts professors who see the Force as something foreign and potentially dangerous.
One common opponent could be other dark wizards. These wizards might also be skilled in dragon dueling and use their dragons to spread chaos. They would see Harry as a threat and try to defeat him in duels.