Loneliness and isolation are big themes. These fanfics often explore how Harry feels being alone, the emotional turmoil he goes through. Also, the theme of inner strength is present. Harry has to dig deep within himself to find the strength to face whatever comes his way while alone.
Hermione could still be a common character. Even in fanfiction where Harry is alone, Hermione might be mentioned in his thoughts or in flashbacks as someone who has influenced him. For example, he might recall her advice on how to study magic when he is facing a difficult spell alone.
Well, in some cases, there could be minor characters from the original series who still interact with Harry on a limited basis. For example, Neville Longbottom might make an appearance. Even though Harry is alone for the most part, Neville could cross paths with him and have a brief conversation or exchange that has an impact on Harry's journey.
Hermione could be one of the characters to help Harry. She's intelligent and resourceful, so she could provide practical help like finding a good doctor or helping with magic - related pregnancy issues if it's in a magical world. Another could be Hagrid. He has a big heart and could offer emotional support and perhaps a place for Harry to stay if he needs it.
One interesting aspect could be Harry's self - discovery journey. In many 'harry is alone fanfiction' stories, he has to rely solely on himself, which forces him to dig deep into his own capabilities. For example, he might learn new spells on his own, without the help of his friends or teachers. This makes for a very different Harry than the one in the original series.
A third theme could be survival. In some 'Harry and Hermione alone fanfiction', they are placed in dangerous situations where they have to depend solely on each other to survive. This tests their skills and loyalty to one another, as seen in 'Surviving Alone' where they are lost in a magically - altered landscape.
In a 'Harry Fights Alone' fanfiction, the plot could involve Harry being betrayed by his friends. Maybe they are put under a spell that makes them turn against him. Harry then has to face the dark forces all by himself. He might have to rely on his own wits and the few spells he has mastered alone. For example, he could be in a situation where he has to battle Voldemort's minions without Ron and Hermione to back him up, and he discovers new powers within himself during this struggle.
Maybe he's frustrated with all the prophecies and his role in the fight against Voldemort. He doesn't want to be constantly pushed into being the hero. He might want some time to figure out who he really is outside of all these expectations. Also, he could be feeling a bit overwhelmed with his studies and the extra - curricular activities like being in Dumbledore's Army. All these things together make him long for some solitude.
Well, perhaps in this fanfiction, Harry has had enough of the constant battles and drama. He just wants a break from his friends too, not because he doesn't love them, but he needs time for himself. He could find an abandoned cottage and start a simple life there, growing his own magical plants and spending his days reading ancient magic texts that he never had time for before. He's basically trying to find peace away from all the chaos.
Voldemort could still be a great antagonist even in a story where Harry battles alone. His power and the threat he poses are well - established in the Harry Potter universe.