The Night Lights are the offspring of Toothless and the Light Fury. They live in the Hidden World and share some abilities of their parents. Like their parents, Night Lights have powerful plasma blasts. They fire first to warn and only openly attack when threatened.
About a decade after Toothless parted ways with Hiccup, he reminisces over the old times by drawing a picture of his rider and New Berk in the sand.
Dart, bored with the daily routines of living at the Hidden World, grows curious about the picture's origin. One night, while their parents are sleeping, Dart convinces Pouncer and Ruffrunner to sneak out of the Hidden World and fly to New Berk with her to learn more about their father's past.
They arrive in New Berk as Hiccup and the other Vikings are preparing for the Snoggletog Pageant. They manage to get close to Hiccup undetected (with Dart recognizing Hiccup from Toothless' picture), but they retreat upon seeing Hiccup's mechanical Toothless puppet, mistaking it for their father. They fly up to a cliff side after avoiding a sheep giving out their location.
On the cliff side, they run into their parents, who are angry at them for running away. Before Toothless and the Light Fury can discipline them, the Snoggletog Pageant begins. The dragon family decides to stay and watch the performance.
The pageant quickly turns chaotic when Gobber accidentally lights the stage on fire. The Night Lights watch as their father rescues Hiccup from falling off a cliff and fills in for Hiccup during the show's climax, where Toothless teaches them about the bond dragons forged with the Vikings. Their family flies away shortly after Toothless meets Hiccup's daughter, Zephyr.
Before they leave, the family stops at the Haddock residence, where they eat a bowl Hiccup prepared with Toothless' favorite fish and leave behind a glowing crystal from the Hidden World as a gift. The Haddocks arrive home in time to watch Toothless, the Light Fury, and the Night Lights fly away from New Berk and back towards the Hidden World.
Shortly after Toothless' family visited New Berk; Hiccup, Astrid and their children return the favor and visit their dragons at the Hidden World. When they arrive at the entrance, Toothless doesn't recognize Hiccup at first and assumes a defensive stance on their boat to protect his family. Toothless eventually does pick up on Hiccup's familiar scent and happily reunites with his former rider.
Hiccup and Astrid are then seen respectively flying Toothless and Stormfly with their children, with the Light Fury and the Night Lights following them.
Dart shares most of her physique with her father while carrying several traits from her mother. The only female among the siblings, she has black as her predominant body color, while the medial and posterior areas are white, faintly tinged in pink. She is the only one of the siblings to possess blue eyes, which she inherited from her mother.
Dart has a naturally calm disposition, but she is also full of curiosity and audacity. In contrast to her inseparable brothers, she strongly cultivates her individualism, as most of the time she stays out of the way when they play and tease each other, but like them, Dart loves a good adventure and does not fear exploring foreign lands. She willingly gives her brothers ideas on spending time and guides them thereafter, indicating that she may have the highest authority among her siblings.
Dart is the only dragon in the franchise to show any form of discontent with life in the Hidden World, which she appears to find dull. She is fascinated by humans and Hiccup in particular.
Abilities and Skills
Cloaking: The Night Lights are capable of cloaking in the same manner as their Light Fury lineage. After flying through a plasma blast, their scales become representative of their surroundings, allowing them to temporarily disappear from sight.
Speed and Agility: Even as babies, the Night Lights can effortlessly keep pace with their parents and perform simple aerial stunts such as spinning in the sky without signs of slowing down.
Strength: The Night Lights are strong enough to carry one of their own with their claws.
Endurance and Stamina: The Night Lights have enough stamina to fly from the Hidden World to New Berk on their own.
The Night Lights are very close to their parents, who in return care about them equally. All three of them are very inquisitive about their father's story on humans, which led them to venture out from the Hidden World. When Toothless and his mate realized that their offspring were missing, they grew worried and scolded them for leaving home without permission. However, the Night Lights mended their errors when they witnessed the Snoggletog Pageant, particularly the scene that showed how their father brought peace between humans and dragons.