To start things off, I shall open with the following cuz it's been on my mind:
YOU! you have OCs, right? Gather a group of 'em with you (or a designated DMing OC) to a table and start playing D&D! (or another ttrpg of your choosing!) ...with yourself, technically; I suppose putting it that way makes it sounds incredibly lonely. BUT!!! Iiiiii think it might be a good opportunity---even if you only really do the character creation phase---to see how those characters interact with each other in such a setting, and how they think creatively... or how creatively they think. It could lead to a lot of things! Do they themselves roleplay surprisingly well? Do they end up murderhoboing or derailing the session? Do they make the goofiest out-of-left-field combination that somehow works? Is their understanding of good, evil, law, and chaos different from a human's enough that they would be confused by those parts of the game? How do the discussions and conversations go in the character creation process and onward? How do their characters and their way of narrating them reflect how they themselves think? How many layers of pretend are you going to dive into? I think this could even help you yourself get a feeling/prepare for how both playing and DMing works, if you someday desire to play a game with real people.
Six (seven-ish) of my Hollow Knight OCs are actually based off the general idea of a D&D adventuring party; they call themselves the Wasteland Wanderers and they consist of two Vessels (One-Horn and Strange Vessel), a scorpion (Ruth), a nosk (Ryku), a tarantula hawk wasp (Chakara), and a woolly aphid (Sordes Regium). On top of them, there's my own Sona, who I've made another Vessel.
So I, as my Hollow Knight Sona, invited them over to the Extradimensional Tavern (which isn't part of the HK world and I'll post about it eventually and may or may not remember to link-) to play Out of the Abyss, my favorite D&D adventure that to no surprise makes me think about Hollow Knight and SilkSong due to a number of its elements! So already there's a plethora of intertwined layers here.
Character creation! I open a private little corner of Discord and use Tupperbox as a means of playing out the dialogue between myself and the Wasteland Wanderers as they read over my copy of the 2014 Player's Handbook and create their characters.
Sordes is definitely the most invested in following along with the established lore and setting; he considers a dwarf at first, but ends up making a drow ranger that ended up seeming a biiit of the edgy-teen type (teen for an elf, anyway). One-Horn and I had to convince whatever's holding Strange Vessel hostage in their own mind to let them free enough to play, and they decided on a motherly halfling druid who runs a farm for her family and community. Ryku, Sordes's (genuine) best friend, isn't nearly as easily understanding the game as his fellows, but was determined enough thanks to his friendship to make whatever he considered (with help) "opposite" to Sordes's character, which ended up being a mountain dwarf paladin. Ruth (and Chakara both, to an extent) went the route of rolling up something that sounded familiar to her: a brawny rogue, and went half-orc to further accentuate that strength. After that, the activity was starting to tire me out, especially after having decided to actually dedicate a thread to digital D&D character sheet filling and actually putting down all the information of my characters' characters!!!.... So I took a few days' break, letting my mind naturally return to the project when it was ready to figure out what One-Horn and Chakara wanted. They ended up both making fighters---One-Horn going variant human and Chakara going red dragonborn. Now all that's left are whatever little finishing touches I missed, and seeing if any of the WW wish to elevate their characters to 2nd or 3rd level as the adventure offers. Ruth and One-Horn even collectively decided that their characters knew each other and were about to start travelling together when, of course, they and the others all get captured by the drow! The uh, the main drow. The actually bad drow. No one Sordes's character wants to affiliate at all with.
hmm... where else have I heard of a member of a certain race getting dragged back to that race's old/real home against their will/in captivity? Oh riiiiight, silksong!!!!!
Anyway, I'm looking forward to this myself and hopeeee that this exercise might help YOU understand your own OCs a little better! Or help you understand D&D a little better too, or something. And if you prefer some other ttrpg like Pathfinder, then go for it! I'm just using D&D cuz it's what I have/know/like. Remember to have fun and take breaks when they're needed!