Demon Slayer AU where Kotoha actually listened to Douma's explanations of his human-eating and accepts it, and so she grows old with Douma and they raise Inosuke together as a happy family. Or, AU where Douma did kill Kotoha, but regretted it deeply, and saved Inosuke as soon as possible then made an effort in trying to raise him, and even supports him as a demon slayer. Sorry I'm soft as hell for Dad Douma with his feral son and think it would have been interesting to see Inosuke if he grew up with Douma as a father