If you’ve begun to write original fiction, how have you managed the transition to original characters and worlds? I’m finding I’m having a hard time making them feel real, and to even write anything meaningful/descriptive/emotive. It’s just so easy to jump into a fanfic idea and I know how those characters would react. But all the exercises I’ve found online just feel so silly or fake? Such as “what’s your OC’s favourite pizza?”
Ahh I love this question about the craft! Thank you so much for asking me. Having written two full OC novels (and a nearly finished third), this has honestly been the area I've had to work on most. I think it's true for many writers who start with fic. Fandom provides such a great sandbox to develop certain skills, but it allows us to perform a sort of shorthand for others -- world building and characterizations being the main ones. So yeah, when you go to craft a story from scratch it's really different. In fact, my first OC novel suffered from a lack of description and sense of place, because I was assuming people shared the vision I saw in my head -- a classic fanfiction writer slip!
To get to your question about how to remedy this, I can share what I do and hope it helps you, though I know it's different for every writer.
For characters, I sit with them in my mind before I start writing them down. I get a sense of them as if they are real people/friends that I know. What was their childhood like? What's their family like now? Did they have an absent mom or an unstable adolescence? What is their romantic history (important since I write Romance) and how does it affect their current view on relationships? Are they a facilitator or the fiercely independent type? Is there something they're really good at that defines them? So I don't totally do the 'what's their favorite pizza' thing, but I do try to envision them as 360 degree people. Get a read on how they would handle themselves in certain situations or what it would be like to have a conversation with them. By the time I sit down to write, I want to have a vision in my head of who this person is, so it's like I'm just describing someone I know.
As far as world-building, for my first OC books I chose settings that I'm familiar with. So a lot of creating the world was description of a place I knew -- which as a fanfic writer, I say go more is more in that area. Don't assume that people see what you're seeing. Bring in those little details that pop in your mind and make your setting unique. Involve the five senses in your scenes. Not all of them every time, of course, but if you smell woodsmoke when writing a bonfire on the beach, make sure you include that detail, preferably through a character's lens. Don't be afraid to be a little flowery. I know fanfic writers get tarred with the 'purple prose' brush, but that doesn't mean paragraphs of pure description are wrong or amateurish. Read a little LM Montgomery to be reminded of how they can add such sweetness and depth to a story.
A few real world/tactical things I do:
To facilitate character development: Talk out loud about a character in my car on longer car rides (when alone, lol). Like just describe their entire life story up to the point when my story starts. Something about speaking it is more permanent than just thinking it, but less time consuming than writing it all down. And I don't worry about writing it down, this is just about getting a feel for a character. (Though I have been known to do this with plot stuff too and in that case I do write down/record things I come up with so I don't lose them!)
To work through specific narrative issues I'm struggling with: Take walks with a stated purpose to do with the story in my mind. For example, "during this walk, I need to iron out character A's motivation for this action and think of a few ways to shore it up in the narrative." And then I'll be pretty disciplined about keeping my mind on working through that problem while on the walk. I bring my phone along so I can stop to make notes of important things I come up with.
Fun low stress stuff: I put together mood boards or playlists that make me feel my story's vibes. I engage in shameless facecasting. I listen to songs that evoke the story over and over and OVER again. I grab a fandom friend on Discord and blabber to them about the most random character idiosyncrasies (shout-out to @pacific-rimbaud and @the-static-hum!) When in boring, inescapable life situations (DMV line, work conference, zoom call) I use the time to brainstorm silly factoids about my story. You can even make it look like you're studiously taking notes!
A caveat: For me it's best not to get too caught up in elaborate character/world backstory documents because I can really get in the weeds with that stuff and feel the returns are diminishing when compared against actually writing.
Whew! OK, that was perhaps more than you expected. I apparently had a lot to say on this subject! I hope some of it was helpful. And I hope you keep trying. Also I think it's totally legit to give yourself a break and write another fandom story if that's what's floating your boat right now. I firmly believe those other OC stories will come out when they're (and you're) ready. The important thing is to keep writing.
All the best and thanks again for a stupendous ask.