Agency is nothing more than the many paths players can take in playing out the story of their character's growth. 2 players can start off on the same path, take any number of forks in the road, and up at the same place (not location, but point in their story) or even very different places.

The heroes are reactive, Villains are active was meant to imply that the good guys typically are out to try and stop something that is in motion (stop a mugging in progress) or something that has just happened (bad guy robbed the bank and is getting away).

Villains are the ones causing the trouble (mugging someone) and making trouble happen (come up with a way to rob the bank and get away).

Leads are a way of providing the intitial context for engaging in one of our content elements: a plot or story. Instead of "Go to Dr. X and talk to him, he tells says....and you select the mission", it may be something more along the lines of: you mugged someone and found out they were an employee at a jewelery store and the nitwit kept a note of his pass code to the alarm system in his wallet. Or you went to a news stand and "read a news paper" the Lead would drop in your inventory providing you with the initial detail to start you off on a plot or story.