Prompt: In the future where sonic and the gang have passed, in a place where its may be on par or better than our current reality, Shadow the Hedgehog lives his life in solitude or maybe he has some obscure side hustle that doesn’t really gain that much money but he does it anyway just cuz(with all that time he surely has sowm secret vault with historical shit and the rest of his mass fortune. He could also be a unknown hero or someyhiidk not that deep into the lore enough).
He comes across Niki(Nikki?) that looks exactly like sonic, except for his cute , dorky bangs and shy/anxious personality. At first he almost had a heart attack before calming down and treats Niki like a acquaintance or little brother(cuz he cant help himself cuz sonics like his long dead lover wink*).
Shadow still keeps sonic, just like the rest of his long dead friend close to his heart, wether he has moved on is up to you.
Little does Shadow know that Niki has a split personality named Sonic, who Niki is aware of and is in constant conflict with.
Edit: And this split personality was only developed to protect Nikis brain the overwhelming amount of memories he inherited from his past and in order to seal his powers due to to some unknown plot villains in the present.