A lot of fics approach it like a battle of philosophical temptations, which honestly feels kinda basic sometimes. They'll have him using a Force push to save someone, then immediately feel a surge of dark side energy that leaves him trembling with guilt. It's this very binary, addiction metaphor where the dark side is this seductive, almost sentient pull. I get why writers go there—it's the clearest canon parallel to his fall.
What I find more compelling are the authors who treat the two sides not as separate powers but as different aspects of the same ability, warped by intent. I read one fic where Anakin, post-Mustafar and more machine than man, used Sith sorcery not to torture or dominate, but to physically hold Padmé's decaying ship together in a memorial shrine. The act was fueled by obsession and possessive love—pure dark side fuel—but its purpose was preservation, not destruction. That gray area where the 'how' contradicts the 'why' is where his struggle gets fascinating. The real conflict isn't choosing a side, but living with the consequences of the power he draws on, regardless of its source.
Those stories often show his internal dialogue collapsing. The Jedi mantras about peace become hollow, and the Sith teachings about passion feel selfishly corrosive. He's left in this silent, pragmatic middle, using whatever tool stops the immediate pain or saves the person in front of him, which ironically is exactly what makes him such a terrifyingly effective villain later. The struggle is less about balance and more about him becoming an unnerving, functional blend of both.