Fun fact, 90% of my initial feature ideas that I want(ed) to build for mastodon are entirely RP-centric. Like, an interface to parse specific hashtags as a "location" so you can easily RP with people in a fictional cafe in the instance's setting, for example.
I also was tossing around ideas for formatting lines within your posts as internal monologue or OOC comments, so like if you put
💭 this place is a wreck
it would italicize that line, or maybe also you could do
💬 This place is a wreck
and it would bold it since it's spoken text, stuff like that.
(I hadn't picked a symbol for OOC, though.)
maple classic™ 
@squirrel ooh! The volume off has promise. 🤔 I'm going to tentatively pick that one.