Gaaruru is a Vocal Doll and Mini-Falulu that represents the negative feelings of girls who believe they can't become idols. Gaaruru can be considered a little terror when she first debuts. She's mischievous and a troublemaker and causes many problems for those around her. She's very disobedient and is unwilling to listen as shown with her growling towards and her biting those around her when they try to talk to her. Gaaruru also appears to not be fond of others and would always be by herself according to Falulu. She also doesn't appear to like idols as well as dancing and singing.

Spoiler

Later, after eating one of Sophy's pickled plums, it's revealed that Gaaruru had swallowed a "Spiny Bug" which turned out to be the source of her bad behavior. She then became a lot nicer and felt bad for the way she acted towards everyone and later stated that she was jealous because she couldn't sing and dance, not that she hated it; however after the concert she decided she wanted to become a "Kaijuu (怪獣 lit. monster) idol".

(Source: PriPara Wikia)