I played random childrens' videogame that has multiplayer.

Room/server theme was roleplay about magical school or something, so I made quick Otome Game Villainess knockoff character to play as. Sometimes I stopped to write about specifics and limitations of ability my character just used. And someone played as child dragon my character adopted, and made cat noises.

Next morning, I found myself writing thought-out and serious lore about that villainess, writing her backstory, motivations, early life traumas, rewriting descriptions of all the stupid abilities with practical use-cases and even more thought out limitations...