Cupid is the god of affection and desire. Anyone shot with his arrows will fall in love with the first thing they see
In the episode Whine and Roses, Cupid is hired by Count Geoffrey to make Griddle fall in love with him. He tried many ways of shooting arrows at her, but hit Burnevere, Blaze, and Allfire instead, causing them to fall in love with Cinder and Clinker, a statue, and a moose head, respectively.
Cupid's final attempt was foiled when Flicker knocked him down, and the arrow hit Sir Loungelot instead, causing him to fall in love with Geoffrey. Presumably Cupid was fired after this.