Flinch started travelling with Grotta after he became one of her many victims when she turned him into a mole because he made the mistake of expecting her to "understand something". Since then, Flinch had to comply with Grotta fearing that she would punish him further by zapping him.
Flinch is a very timid character due to his fear of Grotta. He has a stronger moral compass than Grotta, as shown by the fact that the main reason he urges others to obey Grotta is so they won't become her victims like he did. He's also shown to be more pragmatic and reasonable than Grotta.
Flich first appears after Grotta tells him to find a place for the cave crystal she stole from Gnarlie. While doing so, he accidently makes the cave go dark which makes Grotta reveal her fear of the dark. Later, he warns Gnarly that Grotta isn't an understanding person and that he knew because he found that out the hard way when she turned him into a mole. He later seen being ordered about by Grotta who gives him all sorts of unreasonalbe demands to the disapproval of Sofia, who was kidnapped by Grotta. Gnarly and the other trolls confront Grotta and make her change him back to is true form, which is revealed to be a salamander. He is last seen running from Teeny, who wants to put a bow on him.