Sparkle is the first out of a set of triplet fairies who arrive in Fira and the Full Moon. She is illustrated with blonde hair and blue eyes and is depicted wearing a blue dress with a yellow and green belt. Often she is the first to start trouble, though it's unintentional.
In the books
The triplets have a habit of wrecking havoc for poor Fira in Fira and the Full Moon. First they burn a hole through Tinker Bell's brand new triple shine copper sheet. Then they tire out Lily's rare blue poppy flower with their glows. Finally, they accidentally pour growing powder on a raindrop cactus and destroy Elixa's potion workshop.
Like is common for siblings, the three are often seen arguing. Fira has no other choice but to keep them in their room while she goes to help Orren and Precious, and the rest of the miners. While in the tunnels, Fira's glow burns out. Luckily, the triplets were following the miners and Fira. Fira apologizes to Sparkle, Helios, and Glory and then the triplets lead the group out safely.
The triplets do not make another appearance.