Hey there, I think I can answer this one.
From my experience, it feels like there are two paths to getting a decent number of reads (at least on DeviantArt).
Path 1: You write what other people are looking for.
If you hang around in fat fetish community for long enough, you tend to pick up what clicks with the masses. Writing stories about girls getting fat in college, or writing stories about popular IPs/the flavor of the month waifu, are good ways to get attention.
On that note, fanfic readers will definitely stick around for a deeper plot if you keep fatness relevant.
Path 2: You stand out from the crowd.
This is much harder, because it usually involves being a good writer while also having a few extra skills under your belt. However, going down this path means you have a lot more freedom to do what you want and get read.
Typically, ‘standing out’ means that you know how to write and draw well. People are far more likely to take a chance on a writer who can draw, and if your story quality is good, they’ll stick around for future stories and pics.
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Overall, it’s tough out there, but there are definitely readers looking for stories. Along with the other stuff I mentioned, be sure to follow the other basics.
1. Finish stories that you start.
2. For multi-chapter stories, post your chapters on a schedule (Ex. Every Mon/Wed/Fri until done)
3. Respond nicely to comments you get.
4. Try and boost your work on the weekends.
5. Try your best not to compare yourself to others.
6. Keep posting for a long time.
7. Have at least one long-running series if possible if you’re doing original work.
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And that’s everything I’ve got. My handle on DeviantArt is Zero-CZ by the way.
Good luck everyone!