They are the ridiculously adorable offspring of the Night Fury and the Light Fury. It was some debate on what to call them: Day-and-Night Furies, 24-Hour Furies. But in the end, we settled on the Night Lights.[src]
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.
In Dragons: Rise of Berk, the Night Light's egg has a readily visible scale pattern and is roughly the same shape as other common dragon eggs. It appears to have a base color of black with varying amounts of white speckling.
Hatchling to Adult
Night Lights have an appearance similar to both a Night Fury and a Light Fury since they are a hybrid of the two closely related species. They appear to have small fins on their back, like a Night Fury whilst lacking the single spine of the Light Fury. Their tail fins are also much like that of a Night Fury's. They have four ear-like appendages on their head and are piebald in color.
Night Lights are capable of firing explosive plasma blasts very similar to that of their parent species. Night Lights and Light Furies share a similar amount of control in the timing of the plasma blasts' explosion.
Like their parent species, Night Lights possess the ability of "cloaking". Cloaking occurs when their skin heats up, which causes their scales to have mirror-like qualities, allowing them to temporarily blend in with their surroundings.
Speed and Agility
Night Lights are very fast dragons, as babies can easily keep up with their parents in flight and even spin in the air with no signs of slowing down.
Just like their parents' species, Night Lights are unable to fly if one of their tail fins/flukes is destroyed.
Behavior and Personality
The Night Lights' behavior falls somewhere in between that of each parent. They are playful and curious by nature, but fiercely protective when danger is present. They don't appear to be scared of humans and even allow themselves to be touched by them.
Toothless and the Light Fury became mates and have three offspring, which Hiccup named Night Lights, as a combination between the names of their parents' species.
When Hiccup and his family visited the Hidden World, the three babies were playing with their parents. After Toothless recognized his former rider, the two went for a flight, with the Night Lights flying close to them.