Proofreading fiction is a whole different beast from checking a dry business report. It's not just hunting typos and misplaced commas, though that's a huge part of the foundation. You need an ear for the author's voice. If a gritty noir detective suddenly starts using flowery academic language, that's a flag, even if the sentence is grammatically perfect. You have to spot inconsistencies in timelines, character details (did his eyes change from blue to green?), and the internal logic of the world. I once caught a character exiting a car they'd never gotten into three pages earlier. It's like being a continuity editor for a movie, but you only have the script. Patience is key, because you're often reading the same dense passage five times, each time looking for a different layer of error.
You also need tact. Sending back a manuscript covered in red ink without context can crush a writer. The best feedback explains why a sentence feels clunky or a dialogue tag is repetitive, offering suggestions rather than just decrees. It's a collaboration. The goal is to make the story shine, not to prove you're the smartest grammarian in the room. A good proofreader for fiction has to love stories enough to want to polish them, not just correct them. I find it helps to read passages aloud; your ear catches awkward rhythms your eye will skip over.