Rubella is the Jester who can't rhyme to save her own life, but does an excellent job of saving yours on the battlefield, with her awesome healing skills!
After gaining the ability to fly, you'll meet Rubella shorty afterwards, crying on a platform. After some interaction, she will join your party and you'll earn this trophy. You'll soon find that she's a reliable asset, as there'll be an upcoming battle that will prove impossible without her healing skills.
You'll also receive a Lemuria Request from Rubella after she joins your party titled, Rubella's Plight. Completing 3 of these NPC requests works towards earning the following trophy as well.