Okay so, when I say Stiles I mean Void!Stiles. Basically Void!Stiles leaves Beacon Hills and ends up in Japan. A Japanese family find him and saves Stiles by exorcising the Nogitsune. I remember that Stiles and a son of the Japanese family have sex, but they're not in a relationship. Stiles eventually goes back home.
I think at one point when he gets home, Scott throws him into a wall, because he thinks that it's not Stiles, but this may be another fic. I think the story was Sterek, but it may have been gen.
Any help would be great guys!!! :-)