One idea could be a story where Anakin and Ahsoka are reunited after a long time apart. Maybe Anakin has been on a secret mission and Ahsoka has been exploring new parts of the galaxy. When they meet again, they have to work together to face a new threat that is endangering the Jedi Order.
The theme of family also shows up a lot. Since they have a very close bond, it's like a family connection. Some fanfictions explore how they are there for each other like family members, through thick and thin.
They could also be portrayed as friends. After all, they've been through a lot together. They share a bond that goes beyond the typical master - apprentice relationship. In some fanfictions, they might have casual conversations, joke around, and support each other like true friends do.
One common theme is mentorship. Their master - apprentice relationship is often explored in depth. Another is loyalty, as they were very loyal to each other during the Clone Wars.
There are many good ones. Fanfiction gives a chance to expand on their relationship in ways that the official canon might not have fully explored. For example, some stories might explore what could have happened if certain events in the Clone Wars had turned out differently regarding their relationship, or they might focus on their unspoken emotions and how they could have developed further.
I like 'Journey with Anakin and Ahsoka'. In this fanfiction, they go on a journey that takes them to different planets. Along the way, they have to rely on each other more than ever. It's a story that really showcases their growth both as individuals and in their relationship with each other.
One positive aspect is that it can explore their complex relationship in a more family - like or platonic way. For example, it can show how Anakin's mentorship influenced Ahsoka's growth as a Jedi. It can also focus on their shared experiences in the Clone Wars, like how they strategized together in battles.
Archive of Our Own (AO3) also has a wide selection. Just use the search filters to exclude any mature or inappropriate tags. You might find some really interesting fics that explore their adventures together, their growth as characters in relation to each other, and the impact they have on one another's lives in a family - like or friendship - based context.
One great 'Anakin Skywalker Fanfic' is 'The Chosen One's Redemption'. It shows Anakin's journey towards redemption in a really interesting way. It delves deep into his inner turmoil and how he tries to make up for his past mistakes.
One great Anakin Skywalker fanfic is 'The Fall and the Redemption'. It delves deep into Anakin's internal struggle between the light and dark side. Another is 'Anakin's Untold Journeys' which explores his relationships in a new light, especially with Obi - Wan. And 'Anakin: A Different Path' presents an alternate timeline for his character that is really interesting.