It could be that after a great battle, Harry Potter decides to retreat to the woods to heal both physically and mentally. While in the woods, he stumbles upon a hidden magical community that has been living there in isolation for centuries. He then becomes part of this community, sharing his knowledge of the outside wizarding world and learning their unique ways of magic which are deeply connected to nature.
He could meet centaurs. Centaurs are known to live in the Forbidden Forest in the Harry Potter universe, and if Harry is living in the woods, it's very likely he'd cross paths with them. They might teach him about astronomy and prophecy in a more in - depth way than he learned at Hogwarts.
One popular fanfiction with this concept might be 'The Woodland Adventures of Female Harry'. It has an interesting take on how a female Harry would adapt to life in the woods, facing magical creatures in a new way and forging her own path away from the wizarding world's hustle and bustle.
Survival is a big theme. She has to figure out how to find food, shelter, and protect herself in the woods. It's different from the relatively cushy life she might have had in the wizarding world. Also, there's often a theme of mystery. The woods are full of secrets, and she has to uncover them, whether it's about her own past or some hidden magic in the forest. And sometimes, there's a theme of redemption, like she's trying to atone for something by living a solitary life in the woods.
It could be Dobby the house - elf. Maybe he's on a mission to deliver a secret message to Harry and the cabin in the woods is the safest place he can find him. Another unexpected visitor might be Firenze, the centaur. He could be seeking shelter from some dark magic that's spreading through the Forbidden Forest and the cabin is his last hope.
The Weasley family, if they found out about Harry's situation. Ron, being his best friend, would surely want to help. They could bring him food and supplies. Also, Dumbledore, in his mysterious ways, might be looking out for Harry from afar and send some help in the form of magical objects or even magical creatures to protect him.
One idea could be that Harry discovers a hidden magical artifact in the cabin that has the power to change the past. Another could be that the cabin is a secret meeting place for a new group of wizards who are planning to overthrow the current Ministry of Magic. Or perhaps there are strange, non - magical creatures living in the woods around the cabin that Harry has to befriend to solve a mystery.
He might encounter magical creatures that are native to the woods. For example, he could come across a family of bowtruckles, those small tree - guardian creatures. He'd have to learn to survive on his own, perhaps finding ways to build shelters and forage for food. Maybe he'd discover a hidden magical spring in the woods that has special healing properties.
Well, in some 'Harry mpreg in the woods' fanfiction, the woods could be a place of refuge for Harry. He might encounter a long - lost magical creature there that has the power to initiate or support his mpreg situation. It could be a story full of mystery and self - discovery as he navigates this new state while in the seclusion of the woods.