There aren't any as far as I know! Most writing related threads tend to die out in a matter of months if not days, so I feel like your best bet is to either try to seek out writing related discord groups that sometimes pop up in General and/or advertise writing commissions (if you do them) on Art Marketplace.
I feel like with fics in particular you'll probably find a better audience on sites like AO3, since TH is strictly an OC site and doesn't even allow art and writing that doesn't feature original characters.
Nevertheless, I hope you find your audience & the best platform to showcase your works!! As a fellow writer I know the struggle especially on sites like this that heavily focuses on visuals