Chimera is rude and jealous of Stella, and wants everything her way. She ironically calls Stella a spoiled brat. They became enemies in the first episode of Season 3, where they got into a fight, and later raced for a one-of-a-kind dress they both wanted for the ball, which Chimera got due to Bloom and Stella stopping to save two puppies she nearly sent falling to their deaths.
Chimera was determined to ruin everything for Stella, but a spell she tried to cast on her backfired and gave Chimera a Medusa hairstyle. Later, Chimera and Cassandra allied with Baltor, who gave them the power to make Stella miserable and Chimera princess of Solaria in return for their allegiance and leading them to Solaria's power. Chimera cast a spell to turn Stella into a monster, and Cassandra put King Radius under a spell, enabling Chimera to replace Stella as princess of Solaria.
When Radius and Cassandra were about to get married, the Winx crashed the wedding. Stella fought Chimera and defeated her with a fireball, breaking her staff and reducing her to tears. Chimera and Cassandra were then thrown in the dungeon by Radius, once Stella broke Cassandra's spell on him.