Honestly, I've always found the appeal of William Afton and Mrs. Afton fic to be the massive, gaping void of information about her. The games tell us so little; she's more of a spectral absence than a character. So writers have to invent everything—her name, her personality, why she stayed, why she left, whether she knew. That invention becomes the entire point.
Some stories paint her as a co-conspirator, a Lady Macbeth figure who actively enabled the horrors, which creates this terrifyingly toxic but united front. Others frame her as a victim trapped in a gilded cage, watching her husband unravel and her children suffer, which amplifies the domestic horror. The family dynamics aren't just background noise; they're the main event, often dissecting how neglect, ambition, and madness trickle down to ruin the kids. It's less about romance and more about constructing the rotten core that poisoned the whole family tree.
I read one once where Mrs. Afton was a botanist, and her greenhouse was the only bright spot in the house, but William started bringing 'materials' for his experiments there. The metaphor was a bit on the nose, but it worked.