So I was looking for a fic which I'm sure was on AO3, but I suppose it might not be. Tony had invited the Avengers to live with him and revealed that he held an actual medical degree. Natasha agrees to an exam (I believe it was meant to be gynecological), but during a scan, it's revealed that a spider bite in her youth left her hairs sensitive to certain frequencies. Later, they take Peter in as an intern, and on an elevator ride, they determine that he too has sensitivity to the same frequencies - I think it was to prove he was Spiderman? Any help would be greatly appreciated!