oh man do i have a few!! i'm just going to get the epilogues out of the way first as OBLIGATORY if you want to understand these characters, a lot of people don't even take them into account for their "analysis" which is crazy to me? if you have not read the epilogues u have genuinely nothing to say abt homestuck

now i can only list down fanworks bc im on the train on my way to work but yes!! other than Yours Mine and Ours there's Y1200 and JADE ROUTE which r what i think essential if you like dirk roxy and jade specifically u can find them under the spicyyeti collection in fraf here! https://www.fruityrumpus.com/project/spicyyeti

and speaking of jade obviously LIMINAL SPACE by logan which u can also find here https://www.fruityrumpus.com/project/liminal-space i need to reread them bc it's been a while but yeah it's another thing i would consider mandatory

for jake and grandpa harley i'd recommend Don Juan Manlet King which was discontinued but the first few chapters i feel like bring out a lot (also a good insight on grandpa harley and beta roxy which is admittedly something not many ppl look into), u can read what's out in here https://mspfa.com/?s=32979&p=1

and speaking of discontinued (RIP) House of Dirk which is just a good read and a fun exploration of dirk and caliborn https://mspfa.com/?s=31599&p=1

i haven't gotten very far into Riddle of Dixy yet but its also an exploration/insight of beta dirk and roxy and their life under skaianet and a friend who i trust highly vouches for it :P (english translation discontinued, it's still being published in russian i believe) https://mspfa.com/?s=34948&p=1

(addendum i think reading skaianet is important too! read skaianet!!)

and the last one that comes to mind is the paradox space comic vrisky business found here! https://imgur.com/gallery/vrisky-business-paradox-space-comic-Gf4CXOP