Badass Adorable: Adorable? Check. A kick is stronger than the Hero of the Sword's swing? Check. Twenty levels lower but you are still stronger? Check
Big Eater
Clingy Jealous Girl: She hates anyone else other than Raphtalia getting too close to her Master.
Good Wings, Evil Wings: Has one of the angel variation in her human form
Happiness in Slavery: Is very content being Naofumi's slave. She even complains and gets bored when the wagon she pulls becomes too light.
Head Pet: Starts out as one for Naofumi until she gets too big.
Poisonous Person: She wanted to become the type that would spit poison and would have chosen that for her Class Up had it not been for her Ahoge
Running Gag: After the first time Firo kicked Motoyasu at least 5 meters away, Naofumi explicitly instructs her to do the same thing every time they meet. She does so.
Younger Than They Look: Would you believe that she is a practically a toddler?