I'm not entirely sure specifically what 'ash uses aura fanfiction' is about without more context. It could be a fan - made story where the character Ash makes use of aura in some way that's different from the original source material.
There's no canonical indication that Ash uses his aura abilities to see fanfiction. Fanfiction is a concept within the fan community, not something directly related to the in - universe powers in the Pokémon world.
Sorry, I don't have any specific 'ash uses aura fanfiction' to recommend. You could try searching on fanfiction websites like FanFiction.net or Archive of Our Own.
In this fanfiction, Ash's aura could be like an invisible shield around Dawn. His strong connection with his aura allows him to project it towards her. If there are any attacks, whether physical or from special abilities, the aura could absorb or deflect them. It's as if the aura becomes a safeguard that he can manipulate to keep Dawn safe.
I'm not sure specifically as I haven't read this particular fanfiction. But generally, it might involve Ash using his aura to communicate with the tree, perhaps to gain some sort of power or knowledge from it.
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.
One scenario could be that Serena is trapped in a collapsing cave. Ash uses his aura to sense the safest path to reach her and then uses aura - enhanced strength to move the large rocks blocking her way. Another is when Serena is poisoned. Ash's aura could be used to purify the poison in her system, similar to how some Pokémon can use their powers to heal. He focuses his aura on her body, and the positive energy slowly drives out the toxins.
If it were possible, perhaps Ash could use his aura to tap into some sort of psychic network where fanfiction exists. But this is really just wild speculation as there's no basis for it in the Pokémon lore.
It could be that there is a young, impressionable character who looked up to Ash Aura. After the betrayal, this character is confused and starts to question his own beliefs. There might also be a powerful mage in the story who has the ability to see the truth behind Ash Aura's actions and is trying to prevent the chaos that the betrayal has caused.