I’m almost ashamed to admit how little I know about other stories on Tumblr. I know some exist and I used to follow a couple. But they all seem to have stopped updating. Conner used to write on several and he still has a list of other stories on his site (although I don’t know how up-to-date it is). I know of a couple that are/were planned, but haven’t heard that they’ve started yet.
Feel free to share any good ones and I’ll pass them along!