Spider-Man and Daredevil discover each others identities (Spider-Man actually first learnt Daredevil’s identity way back in the Silver Age in Daredevil (1964) #24 but it was a development forgotten about)
[from The Spectacular Spider-Man (1976) #110]
Peter: Let me understand - you could tell when you heard my heartbeat as Peter Parker and later as Spider-Man that we were the same guy? That’s some power. What do you call it?
Daredevil #113 (2009)
↪ Written by Ed Brubaker
↪ Art by Michael Lark; Stefano Gaudiano