Lucy Wilde is a junior agent with the Anti-Villain League (or "AVL"), an organization "devoted to fighting crime on a global scale".  She has been tasked by her boss, AVL Director Silas Ramsbottom, to make contact with Gru and recruit him into the AVL for a special mission: to recover the stolen PX-41 serum, a very dangerous mutagenic compound.  In their initial meeting, Lucy gets the drop on Gru very quickly with her lipstick taser, which she later admits to having thoroughly enjoyed. She then abducts him in her special car (which doubles not only as a miniature submarine, but also as a jet plane with just the press of a button or two!) to take Gru back to the AVL's mobile submarine headquarters.

However, in spite of initial abrasive difficulties (brought on by Gru's dislike of working with others who are his equal, and able to get the drop on him), a romantic relationship soon develops between Lucy and Gru, leading eventually to marriage after he nearly loses her during the course of their adventures together.  Gru saves Lucy's life after El Macho tries to repeat the same epic ending he faked for himself years before, by tying Lucy to a live shark strapped with dynamite, and then to a large rocket, aimed at an active volcano.

In spite of her junior agent status, Lucy shows herself to be every bit of Gru's and even El Macho's equal...she's resourceful, she's clever, and she's brave.  And she has a great sense of humor, remaining almost flippantly upbeat even under terrible pressure!