Fanfiction usually develops Anakin's character by showing his relationships in a new light. His bond with Palpatine could be shown as more complex, with Palpatine slowly manipulating Anakin over a long period, preying on his weaknesses like his desire for power to save Padmé. This makes his turn seem more gradual and believable.
In these fanfictions, Anakin's character is often developed by exploring his reaction to the Jedi Order. If he feels restricted by their rules and sees the dark side as a way to break free and achieve his goals, his turn becomes a way of rebelling against what he perceives as a stifling system. This gives a different perspective on his character compared to the original story.
Some fanfictions explore Anakin's turn from the perspective of his friendship with Obi - Wan. Maybe there's a rift between them caused by outside forces, like a false accusation against Anakin that Obi - Wan doesn't fully believe him about. This slowly sours their relationship and Anakin, feeling abandoned by his friend, is more susceptible to the dark side's allure.
Often, it starts with the shooting incident. Then, it may show the immediate aftermath, like Anakin being rushed to medical help or his comrades trying to protect him from further harm.
Their relationship becomes more possessive. In the Dark Side, Anakin's love for Padme could turn into an obsessive need to control her. He might see her as his possession rather than an equal partner.
In some fanfictions, Ahsoka might save Anakin through the power of their strong bond. She could remind him of their shared memories, the good times they had together, and the Jedi values they once held dear. By appealing to his emotions and the part of him that was still good, she could potentially pull him back from the dark side.
Often, Anakin's development in these fanfictions involves him exploring different aspects of the Force. He might discover new Force abilities that were not part of the original story. This new knowledge helps him to dominate in various situations, whether it's in combat or in diplomatic negotiations. Also, his relationships with other characters, like Obi - Wan or Padmé, are often explored more deeply, which in turn shapes his character growth.
In fanfiction, Anakin joining the Dark Side often has complex motives. It could be due to his fear of losing Padmé. The Dark Side might seem to offer him a way to save her, so he succumbs to its power.
A possible plot twist could be that Obi - Wan was actually faking being turned to the dark side all along. He was trying to infiltrate the Sith ranks to learn their secrets and stop them from within. He lets Anakin think he has succeeded in turning him, but in reality, he is still a Jedi at heart and has a plan to take down the Sith.
The fanfiction could explore an alternate timeline where Anakin has stronger support from the Jedi Council. If they recognized his potential and didn't hold him back, he would be more likely to stay on the light side. It could also show how his relationships, like with his mother or with Padmé, could be developed in a way that keeps him grounded in the light. For instance, if his mother was saved in a different way and he didn't have that anger and fear, it would help him resist the dark side.
Anakin might develop more self - control earlier. Yoda's wisdom and unique training style could help him better understand his emotions and not be so easily swayed by fear, which was a major factor in his fall to the dark side in the original story.
Anakin in these fanfics may also be shown as a more vulnerable character. The harem might be a support system for him, and through their interactions, his softer side is revealed. For instance, when he is with the female characters in the harem, he might open up about his fears and dreams more than he does in the main storylines, adding new dimensions to his character.