Character Idea

I spent 2 hours refining a plot I made for a novel with Gemini, and then realized it would be a waste to just submit the character alone, so I stopped lol (It felt like I could write a whole series, they even helped me compile a setting book) Now I have to come up with a new character idea from scratch again... Hmmm... I only like characters that have an intricate world-building and can create a rich story. I'd probably get bored of making trendy characters first myself 💦 Does anyone have any ideas?