Fate/stay night - All Night Long (Doujinshi)

[MangaDex]

 

[Pokari]

I am disappointed that the description is tongue-and-cheek (though not strictly undeserved) because that would have been so godawful weird as to be memorable.

Instead, this is just one of those random-assortment-of-idle-thoughts stories, as suggested. I suppose it's not bad, nor particularly offensive, as these things go.