One possible plot could be that Ash discovers his hidden ability to be an Aura Guardian gradually. Maybe he starts having strange dreams about it at first. Then, in a battle, he unconsciously taps into his aura power to save his Pokémon. This new power would lead him on a journey to understand more about the Aura Guardians, their history and his place among them.
One great aspect of Aura Guardian Ash fanfiction could be the exploration of Ash's latent aura powers. Maybe in these stories, Ash discovers he has a much deeper connection to the aura realm than he ever knew. This could lead to him having new abilities and forming unique bonds with Pokémon that are also attuned to the aura.
Some of his Pokémon might sense the change in Ash immediately. Pikachu, being his closest partner, could be both curious and a bit protective. It might stay closer to Ash during battles, as if it knows Ash has a new power to draw from. Other Pokémon like Charizard might be a bit more aloof at first, but as they see the benefits of Ash's aura powers in battles and in protecting them, they would come to accept and rely on it.
It depends on your personal taste. If you're a big fan of the Aura Guardian concept and like stories centered around Ash, it could be a great read. Some fanfictions really capture the essence of the characters and expand on the lore in interesting ways.
In some Aura Guardian Ash fanfiction, Ash could be part of a prophecy. As an Aura Guardian, he might be the key to saving the Pokémon world from a great threat that is related to the disruption of the aura. This would put him in a position where he has to make sacrifices and grow in ways he never expected, all while relying on his newfound aura abilities.
In 'ash the last aura guardian fanfiction', a frequently seen theme is friendship. Ash's friends play an important role in his journey as the last aura guardian. They support him, and together they face challenges. Also, the theme of redemption can be present. Maybe Ash has to make up for past mistakes while being in this new role. And there's often a theme of power growth, as he gradually becomes more proficient in using his aura guardian abilities.
I'm not entirely sure specifically what this 'ash aura guardian harem lemon fanfiction' is about as it could vary greatly. However, generally in fanfiction, 'ash' might refer to a character named Ash. 'Aura guardian' could be some sort of special role or power related to that character. And 'harem' usually implies a story where one character is surrounded by multiple love interests. But the 'lemon' part often refers to sexual or adult - themed content, which is not appropriate to discuss in detail.
One possible plotline could be Ash discovers his latent Aura Guardian abilities gradually. He might start having strange visions or experiences related to aura. Then, he has to find someone to train him, like an old Aura Guardian who has been in hiding.
Well, 'Aura Guardian Ash: The Legendary Bond' is also a popular one. In this, Ash forms a special bond with a legendary Pokémon through his aura. This bond allows them to communicate telepathically and work together in battles. It's interesting as it delves into the emotional connection between Ash and the Pokémon, all because of his role as an aura guardian.
Ash could be developed by showing his struggle with the new responsibilities that come with being an Aura Guardian. For example, he might have to make tough decisions about protecting Pokemon that could put him at odds with some people.