It's a bit tricky to pin down Newt Scamander's exact age in the novel. However, we can make some educated guesses based on his experiences and the time period the story is set in. My estimate would be that he's around 23 or 24 years old.
In a fanfiction, Newt could be called upon by the Ministry of Magic to handle a dragon that has escaped from a wizarding zoo. He would have to track it down in the wild, and when he finds it, he realizes that the dragon is injured. Newt would then have to use his healing skills and his bond with magical creatures to nurse the dragon back to health while also making sure it doesn't cause too much chaos in the non - magical world. This could lead to some interesting encounters with muggles and challenges in keeping the dragon's existence a secret.
One common theme is the exploration of the magical world. Fanfics often describe Newt's adventures in different parts of the wizarding world, uncovering hidden magical places and creatures.
Perhaps there's a prophecy in the wizarding world that only a dragon rider can stop an upcoming war. Newt, being the expert on magical creatures, is sought out to be this dragon rider. He initially resists, but when he realizes the importance of the task, he embarks on a journey to find a suitable dragon. Along the way, he meets other characters who help him in his quest, and he has to learn the ways of dragon riding from scratch, which is full of both comical and dangerous moments.
First, know the character of Newt Scamander well. Read the original books and watch the movies to understand his personality, his relationship with the beasts, and his role in the wizarding world. Then, create an interesting OC. Give them a unique backstory, appearance, and set of skills or powers.
Newt's calm and somewhat eccentric nature would rub off on Harry. Harry, who has faced so much turmoil and danger, could learn from Newt's ability to find peace in the study and care of magical creatures. This could make Harry more level - headed and less impulsive in his decision - making, especially when it comes to dealing with threats like Voldemort. Newt might also encourage Harry to think outside the box. For example, instead of always using traditional magic to solve problems, Harry could start looking at solutions from the perspective of magical creatures and their unique abilities.
Their interaction would likely be very interesting. Newt is quite shy and introverted, while Harry is a natural leader. Harry would probably be curious about Newt's magical creatures and Newt would be in awe of Harry's ability to face danger head - on. They might start off a bit awkwardly, but as they get to know each other, they would find common ground in their love for the wizarding world and their desire to protect it from harm.
He would likely be very interested. Newt is a lover of magic and all its forms. Fanfiction, which is full of new takes on the magical world, would draw his attention.
One common theme is the exploration of Newt's relationship with his magical creatures from a female perspective. For example, how a female Newt might have a different approach to taming or caring for them. Another theme could be her interactions with other characters in the Fantastic Beasts universe, like Tina or Jacob. There might also be themes related to her facing the challenges in the wizarding world as a female magizoologist, which could include discrimination or unique opportunities.
Another characteristic is that it can expand on the wizarding world that Newt is part of. It could introduce new locations or magical concepts related to his work. Also, it should have a good plot, like a mystery he has to solve or a new discovery he makes. This makes the story exciting and keeps the readers interested. For instance, a story where Newt discovers a new type of magical creature and has to figure out how to protect it. It would involve his knowledge, his courage, and his compassion for the magical world.