Something fluffy and gory based on this quote from Donovan from The Internet Is Not Just For Porn by cyerus on Ao3 :
"Why would he know about decaying body parts? Oh god, you've found yourself a serial killer boyfriend, didn't you? It makes a horrific kind of sense, he'll kill people and bring you bits of them to experiment on. He probably does the shopping too, because he's a provider, then you'll snuggle on the sofa and talk about your day. He'll tell you about all the people he murdered, you'll tell him about the most gruesome crimes you solved, and it will all be horribly, horribly domestic.
Sherlock/John Serial Killer boyfriend
"Why would he know about decaying body parts? Oh god, you've found yourself a serial killer boyfriend, didn't you? It makes a horrific kind of sense, he'll kill people and bring you bits of them to experiment on. He probably does the shopping too, because he's a provider, then you'll snuggle on the sofa and talk about your day. He'll tell you about all the people he murdered, you'll tell him about the most gruesome crimes you solved, and it will all be horribly, horribly domestic.