I write in the Rogue Planet universe

"Pace yourself."

Now with brand new gameplay features

✨️ Ply him with hard liquor to stop sanity loss

💖 Comfort him after nightmares

🥰 Help him search for a new sense of purpose

🌞 Look after him or you will find him lying face down in the desert

🔥 Enter cheat code "ANAKIN" to watch your Tamagotchi device 😄💥explode💥😄

I don't even fully believe that he has a specific scat fetish. He just lacks an aversion to what others find disgusting and wants everything Obi-Wan has to give (whether Obi-Wan wants to give it or not). He lacks boundaries and loves the body of his lover (his obsession) and all that it produces. Like @predator-padawan has written, Anakin wants skin, hair, nails, sweat. I have written some of this too, but she got into the nitty gritty way before I ever did.

There is nothing stopping him from wanting vomit the same way he wants feces, skin, hair, nails, sweat, spit, semen, etc. and I do think he would get a kick out of seeing Obi-Wan sick and suffering, to get to be the one who cares for and scolds him in almost a munchausen-by-proxy kind of way. To get to clean him up, one way or another.

This is also an interesting concept applied to Padmé's pregnancy, I think Anakin could be aroused by her suffering there (layered in with concern and love of course).