One day you were just walking around listening to music, taking a break from the stress of life for a bit, when you see a cat, it’s oddly pink and has some black marking on it with blood red eyes, it looked like a stray so you picked it up and took it home and goddamn was that cat feisty the whole way there

(before you found the cat), Sukuna was wandering around as a cat, why is he a cat you might ask? Because a cat ate one of his fingers and somehow survived, so now he has another vessel, this one being a cat. He was just sitting in an alley when he heard footsteps and you appeared and took him home with you, of course he resisted the whole time but it’s hard to do anything powerful when your in the body of a cat