I've never had any notable OCs to remember in my decade long conquest of anime and manga. In fact, i usually just imagine myself being in that fictional universe and how things would have happened instead. BUT the first time i did create an OC (or OCs to be specific), I REALLY. REALLY. MADE THE EFFORT.
It was for the anime/manga MAGI, where my OCs were a dungeon capturer(A) and her female djinn(B). As (A)'s background was somewhat similar to a gypsy/circus/exotic dance/entertainment troupe, i had to research on the every minute details related to these subjects to complete my intended concept idea; and as (B) was a djinn of Lepidopteran species, and more accurately a moth, i literally read up on the varying types of moths, myths/legends or moths, scientific facts of moths, animal symbolism of moths, etc. IT WAS CRAZY! But i enjoyed every single moment... ... ... ... ... Wow. It's been a moth(i mean month!) and I'm not even finished! I still feel like there's more to consider as i'm creating them (๑•ㅂ•)و✧
~> [IF INTERESTED AND EAGER: DO SHARE SOME OF THE JUICY DETAILS THAT YOU'VE PAINSTAKINGLY THOUGHT UP AND CREATED! SHOW YOUR PRIDE IN YOUR OC (づ ̄ ³ ̄)づ] <~ Eg. Anime/Manga(/Cartoon/etc.): Magi (with slight cross with AoS) OC(s) details: [A] Ligeia Achelous (ライヒア.アケロオス Raijīa Akerōosu) [B] Murmux (ママス Mamasu) Djinn: Murmur is a sound djinn and the Djinn of Silent Prayers and Whispering Dreams. Murmux was in the 54th Dungeon. Metal Vessel: Ligeia's tongue piercing
~> [THIS IS PURELY FOR THE SAKE OF SHARING PURPOSES. PLEASE DO NOT CLAIM/STEAL OTHER'S WORKS AS YOUR OWN. ALL OCs BELONG TO THEIR RESPECTIVE OWNERS!] <~