Foggy discovers he's a demon. His mom and dad kept it from him because they wanted him to 'fit in with the humans'. It worked very well and they're kind of disappointed he isn't even slightly evil. They're not the 'death and abuse' kinds of demons but Foggy could curse people to say...lose their socks or the like in the wash.

Foggy is true to his word and tells Matt. Matt is confused. then wonders if he's descended from a demon.

(The answer is yes/no, he and Foggy are BFFS because they're BFFs)

(Could be nonplatonic too)