I made Systemless to spite toxic readers on the website Royal Road, but then I found it too funny to end it early so I just kept going with it...
Mine started off as characters for my ripoff Hetalia slice-of-life universe until I decided, "man, I don't wanna research this" then I filled in my own lore, and it morphed into the comic now (or it's going to be, since it's not yet out).
It was nearly 5 years ago that i came up with this. What a world.
Mine started off as an almost blatant rip-off to the manga/anime "Black Cat" by Kentaro Yabuki. I pretty much took the plot and theme and kind of just shoved my own characters into it. I also just really needed an escape and Black Cat was my favorite series at the time.
This was over a decade though and the story and characters have matured a lot. There are still a couple similarities, but everything is gonna have similarities to something else.
My comic started as concept art for a fantasy MMORPG project me and some buddies wanted to make back in late-middle-school/early-high-school. (We didn't know an ounce of coding or game design, but y'know.) I was in charge of most of the concept art and world design, and though I wasn't considered the "lead artist," I was by far the most artistic. I came up with a technologically advanced civilization, but my ideas were largely discouraged by the other members; they wanted a more traditional medieval setting.
After I left, I forgot about the ideas for a while. Then like two years later I suddenly remembered the concepts. I decided I was going to make a story out of the world, so yeah. A lot has developed and changed, but some things have still remained; I like to think the "spirit" of that original world is preserved.
Here's "Aegis."
Mine started as a theater project! I had some ocs before this time, but I didn't have a story in mind. In 8th grade, I took my first and only theater class which was so incredibly fun. We had split teachers since we didn't actually have an official theater teacher so my chorus teacher and an english teacher split the students and switched out every other day. In both classes, we had to come up with a character to act as. The first teacher had us create a character based off of someone we knew. That's when I designed Seth, one of the main characters of my comic. Later on in my second theater teacher's class, we designed another one, and I decided to go for a character completely opposite of Seth, which is my main character Joyce. Since they both were created in my theater class, I decided to make them siblings cause they came from the same idea and kind of project. After that, I incorporated them with my other ocs, and I loved creating a story with them (minor future characters spolier-ish?): my first comic idea with my characters was Joyce, Seth, and their friend Storm being trapped in a room with my demon oc Melissa who was trying to possess Joyce. Alex, Joyce and Seth's babysitter, trapped outside of the room, trying her best to break in. It never got fully fleshed out until about a year later when I created a whole bunch of characters and started world building around them. I'm really proud of how far my story has come so far, and I'd like to present to you my comic: The Hidden Monachopsis
I didn't like journals as a kid because people would read them. (You were required to have them in school and the teachers would read them and comment on them. I hate that. So I would basically just throw some 'choice words' directed at my teachers for my school journal instead of actually writing in it)
Then because of that, the idea of having one at home was absolutely terrifying, cause school basically taught me that journals are basically there for adults to read.
So having no personal outlets I just put it all into my characters and called it a story. Just a depressing nothing will get better, I'm so alone, LGBT kid living in the closet feels disguised with a plot.
It was pretty genius thinking back. For some reason adults were obsessed with getting in your business and wanting to read personal stuff like blogs and journals, but no one gave a fuk about any stories you were writing to the point where even if you wanted a parent or teacher to read you stories no one would and would pull every trick in the book to avoid having to read it.
Fast forward to now, found it cleaning up, decided "you know, I could actually work on this and make it into a legitimate story" and well, here we are.
My story started as a bunch of different dreams I had. I tend to dream almost in movies, where I am not involved but can watch all that is going on, and rewind if I do not like it...
Anyway, I had two different dreams about my OCs for some show...
One in which Mikhail was an Angel, and going to the yearly prom of peace between heaven and hell in order to find himself a date
The other in which Stefan and Mikhail were roommates and Stefan was a superhero who pretended he was just really into cosplay as a way to hidehis secret identity from the other.
In the end I wrote a story about Mikhail being an Angel whose roommate on Earth is Stefan and tries to blend in in the human world even though Demons keep trying to kidnap him. ^_^
Also, I wanted to challenge myself into writing a love story because I generally hate those, so I decided that they would end up together 
Mine started off as one of those middle school "I made a comic and put all my friends in it" and now we have powers like Sailor Moon. Back then, in my circle of artist friends, it was kind of an unspoken rule that all of the comics we made would include character versions of ourselves and people we knew.
Many (many lol) years later I worked to develop into something that makes sense and be its own story and own characters. Despite it's crappiness and cringe, my friends really loved the comic and have been asking me to finish it for decades (as I left them hanging back in the 90's).
Oh, interesting...
In my case, Back to 2019, i was in a certain Artist server. Around the end of the year, the Adm decided to start some Role Play. Then i created my Character.
The RP didn't really end well because of me and the character(I noticed i created stuff that 'd be troublesome to the others members' characters), but since i had already created so much about him, i thought "Huh... i think i can put him into one of my universes... This one!"
I was already wanting to start a webcomic, and used him as a prototype.
Then, i created my Doctor A in Webtoons, but moved him to Tapas.
My comic Hollow kind of started out in its initial concept as speculative fanfiction too. The instigating thought was, "What would Card Captor Sakura be like in her twenties and the magic is gone? How would spending her formative tween years doing magic and risking her life affect her as an adult?" And then it snowballed from there.
I like a good LGBT romance, so I made the main character male so he can crush on his "Shaoran" equivalent, and I made his tween magic years reminiscent of classic magical girl anime, with similar tropes and events, but with lingering and cumulative consequences that ultimately left him depressed and broken, with PTSD and panic attacks.
Then the story turned into a whole statement on nostalgia, leaving your childhood behind (or not?), moving past trauma, and glamorizing the past. As it is now, I think it's fair to say that Sailor Moon and Card Captor Sakura were definitely instigating influences to the story, but Hollow has become its own entity that stands on its own. In my opinion, anyway!
My novel started as a chaotic mess of memes and jokes in a YouTube video series. It was made to emulate the old RPG video game styles of Final Fantasy and Fire Emblem. All the while following the logic, inside jokes, and RNG of a D&D campaign. It even got to the point where it was fully voice-acted near perfectly, and voice actors behind two of the main characters enjoyed the ridiculousness of it.
However, things started getting a bit too chaotic and I decided to rewrite the entire story from the beginning. A few months later and now I have this novel getting a new, full chapter every week. The characters are still the same as when they were originally created, and there's gonna be comedy sprinkled in. But it's not gonna be nearly as chaotic and messy as it was originally.
My novel started off as escapist daydreams and developed through the years. I originally made some of the main characters up in middle school and I think the only thing that hasn't changed from their conception is their hair color.
My comic has pretty much been the same throughout the time I've written it (superhero comic partially inspired by the movie "Overlord" and a podcast episode I listened to about Unit 731), but my novel, "Godswater", has gone through a lot of changes. Most of the character names have stayed the same, as have the way most of them act, but the magic system in particular has gone through several overhauls. I've rewritten it several times, too, and every time I do, the period in history it's based in goes forward, too. In the first draft, it was a straight up sword-and-sorcery book. Next, it was based on the renaissance/age of enlightenment. Then, it was a little more American Revolution-y. Now, it's based in more like 1880. Next draft will probs have tanks at this rate lol.
Like a lot of things I write or draw, I get ideas from my dreams, which tend to go hog-wild because of my medication for bipolar. I keep a notebook just to write those down. Like some sort of perpetuum mobile, I often get nightmares with elements of nuclear danger, radiation sickness and stuff of this kind, which in turn makes me obsessed with researching them, and that again fuels what I dream about, and so on lol. Also, I'm a huge huge nerd on all things prehistory, palaeontology, astronomy and astrophysics, so a lot of big parts of my worldbuilding is supported by the more unusual theories that I find cool.
Eh. I started writing my novel Jade Kingdoms out of spite. I was so done with my family's BS and their refusing to admit we've all suffered so much over the generations, I started writing my own story about healing. The plot came to me very easily, like it was all coming together and together with my art I am making the story unfold slowly. I began writing it on August 1st 2017, and now we're here today. 
Mine started off maaanny years ago back in 2002. Tenchi Muyo just started airing on Toonami and I really liked their take on space pirates, so I made my own RPG Maker game inspired by it. But being that I was 13, it made NO sense. A couple years ago, I revived it as a manga and fixed all the junk that didn't work together
My story started off a D&d story, complete with content and lore pulled straight from d&d, but with my own twist to it.
A lot of the characters from that time still exist, they were just remade into versions i consider more interesting now, in a world that is completely my own. ^^
It's wild to remember THAT is how it all started... And to try and pair the current versions of the characters with their old edgy selves xD
Mine started off as a love story between MC and Loki, who was basically marvel Loki at this point, and how they went on the run from Odin. Then I thought "That's cliche. Let's do something different." I rewrote it several times, until I was happy with what I had. Now, MC is a lesbian, Odin is the neutral drunk guy, and Loki is back to his mythological roots.