To be really honest aku pribadi masih belum merasa kalau karakter yang aku buat sudah sehidup itu, so having someone asking this is truly an honor to me! And I am not excellent in this topic by any means, but these are things I always try to focus on everytime I try to get into my characters:

• Differentiate their ways of typing, as I feel like one's typing could give a little bit of (if not more) sense about their general behavior; how effective they want their conversations to be, what kind of communication methods they’re using daily, how well they are in personal conversations as well as they are in keeping up with trends, slangs, etc... Or maybe you could also put a twist in it to spice up your character by making some adjustments to it, like maybe making their typing totally different from how they act in real life, or giving them different ways of typing depending on who they’re texting with, get creative!! 😁

• Relate the main characters’ personal background with the main events that's gonna happen to your pairing, so that it’s easier to navigate your pairing’s background and development while increasing their involvement in each other’s personal story— giving them a sense of being fated and destined by far has been something I love to do the most to my pairings!

• *Side characters involvements, not in a way that you put them in the story only for the sake of it, but also to help the story/character progressing. Give different kinds of friendship dynamics (mungkin sambil mempertimbangkan kalo 'kedekatan' itu kontekstual dan relatif, kayak seseorang bisa dekat sama kamu bukan berarti kamu bisa open sama mereka tentang kehidupan personal kamu, atau sebaliknya, punya teman yang nggak pernah sharing soal kehidupan sosial bukan berarti nggak dekat), or different kinds of roles in a circle (misal di dalam circle pertemanan semuanya equally close to you tapi ada beberapa yang jarang muncul, ada yang prefer ketemu langsung, ada yang prefer jawab pribadi daripada nyamber di grup). You could also consider adding key characters, yang jadi kunci dari suatu peristiwa, entah di masa lalu dan yang membentuk latar belakang karakter utama, atau di masa depan yang bakal jadi alasan munculnya suatu kejadian. That’s a lot of work for sure, tapi dalam pengalamanku sendiri ini tuh malah yang bikin nulis jadi asik!

Dah gitu ajaaah. Semalem kurang detail sih jadi ini aku tambahin tanpa harus kasih contoh yang bertele-tele skdjksjdks. Semoga membantu!