Curio is a close friend of Francisco and serves as Juliet Capulet's fencing instructor. He is a skilled swordsman who lost the use of his right eye, and his preferred weapons are axes or polearms. His scarred visage originated from an incident where he protected a younger, rebellious Juliet from receiving punishment from members of the Carabinieri. He blames his own foolhardiness for the blow that caused his injury, and it was Juliet's frustration from that time that gave birth to her alter ego, the Red Whirlwind.

Curio is portrayed as Francisco's counterpart, being the more down-to-earth and serious of the two. He is a man of few words and decisive actions, preferring to observe and analyze life before taking part in it. He never lets his actions get the better of him and remains calm in dire situations, making him a valuable asset to the Capulet household. His entire family was killed by the Montagues, which has given him a personal vendetta as he has sworn to have his revenge on them.

Curio is utterly dedicated to protecting Juliet with his life. He consistently serves as the one who bails the Red Whirlwind out of sticky situations. Beyond his role as a physical protector, he is the one who shows her the world and opens her eyes to the true seriousness of their circumstances, teaching her that if she wants the winds of change to blow, she will need to be less reckless in her actions. He is a close friend of Francisco, and from episode sixteen onward, it is hinted that he may harbor romantic feelings toward Juliet. At the conclusion of the series, he settles down as the owner of his own grocery store.