One possible plot could be that there's a wizard who is known for his charm and love for adventure, much like the idea of a 'play boy' in the Muggle world but in a very innocent way. He could be going around the wizarding world, trying out different magical spells and potions in a carefree manner, while also making friends along the way. His adventures could involve things like exploring forgotten parts of Hogwarts or helping out in magical creature reserves, all while having a bit of a flirtatious personality that is more about being friendly than anything else.
The fanfic could be about a character who is misjudged as a 'play boy'. In reality, he is just very passionate about different forms of magic. He travels around, showing off his unique magical skills which some mistake for showing off to attract others. His real goal is to find a way to combine different magical disciplines to create a new form of magic that can protect the wizarding world. Along the way, he has friendly interactions with many characters, and his so - called 'play boy' image slowly fades as people understand his true intentions.
Perhaps the cloak is a family heirloom that the boy only discovers when he's in a time of great need. It could be a cloak that was enchanted by an ancestor with a specific purpose, like protecting the wearer from a particular dark magic. As he starts using the cloak, he realizes that it comes with a set of rules and responsibilities. He has to figure out how to use it to his advantage while also fulfilling whatever the cloak's original purpose was. This could lead to him learning more about his family's past and his own place in the wizarding world.
Perhaps there could be a fanfic where a new werewolf arrives at Hogwarts. This werewolf is from a different wizarding school where they were shunned because of their condition. At Hogwarts, they meet Professor Lupin who takes them under his wing. Together, they work on a project to create a new potion that could ease the pain and transformation process of werewolves. Along the way, the new werewolf makes friends and learns the true meaning of acceptance within the Hogwarts community.
It could be that Harry Potter finds himself in the world of the Lost Boys. Maybe he uses his magic to help them fight off some new dark force that threatens their home in Neverland. He might teach them some magic tricks in return for learning their survival skills in the wild of Neverland.
I'm not sure specifically about a 'Harry Potter Play Boy' fanfic. But generally, in the vast world of Harry Potter fanfiction, there are a lot of different interpretations. It could be that an author has used this title in a very creative and innocent way, perhaps playing with the idea of a character having a flamboyant or carefree attitude like the stereotype of a 'play boy' but still within the context of the magical world and its values.
The fanfic could center around Harry's life outside of the main events of the books. For example, it could explore his summer holidays in more detail. He could be spending time in the Muggle world and using his magic in creative ways to solve normal, everyday problems. He might use magic to help his neighbor fix a broken fence without the neighbor realizing it was magic. This would add a new dimension to his character and show how he can adapt his magical abilities to different situations.
The plot could be set at a magical school event. Harry, being the hero that he is, catches Fleur's eye when he saves someone from a magical mishap. He then begins to court Fleur in a very gentlemanly way. He brings her flowers from the magical garden, invites her to study together in the library, and they start to have deep conversations about their dreams and hopes. This way, Harry is'seducing' Fleur with his good heart and positive qualities.
One possible plot could be that Harry Potter is hired by Sherlock Holmes to help with a case that involves dark magic. Harry uses his knowledge of the wizarding world to uncover clues that Sherlock couldn't find with just his deductive skills.
Imagine Harry Potter as a bartender. He could be using his skills not just in mixing drinks but also in reading people. Since he has faced so many challenges in his life, he can easily spot if a customer is hiding something or if they are in trouble. His bar could become a place where secrets are shared, and he has to use his wits and magic to keep things in order. He might also have to deal with rival bartenders from other wizarding establishments who are jealous of his popularity and unique drinks.
The plot could involve Harry Potter discovering he has some sort of connection to a dragoness. Maybe he can communicate with her telepathically. They could team up to fight against dark forces in the wizarding world. For example, Voldemort might be after the dragoness for her powerful magic, and Harry has to protect her while also using her strength to defeat Voldemort.
One possible plot could be a deaf Muggle - born student getting their Hogwarts letter. They face difficulties in the beginning as they can't hear the instructions well. But they soon discover a magical device that helps them 'hear' in a magical way, like through vibrations that translate into words in their mind. Then they go on to prove themselves in classes like Charms and Potions, making friends along the way.