Viper was a young female SandWing who was a member of the false dragonets of destiny as a replacement for Sunny. Her parents and possibly her uncle were members of the Talons of Peace, but Viper was only chosen by Morrowseer because of her convenience. She was killed in the Night Kingdom while in a battle training session with Flame, in which she accidentally scarred Flame's snout with her tail and fell into a river of lava during an attempt to kill Fatespeaker.
Viper has pale sand-colored scales with a white underbelly and underside of her wings. She has a lengthy, forked black tongue, a black barb and horns, black claws, along with matching obsidian-colored eyes. She has no known jewels or adornments she wears.
Similar to the other false dragonets, she was very annoyed by Fatespeaker's imprecise and false predictions and found amusement in bullying Squid. She seemed to also take pleasure in abusing Fatespeaker, nearly to the point of killing the NightWing, and despised the NightWings for taking her away from her family. She acted aggressive to anyone she met, and usually kept to herself, but if anyone came too close, she'd threaten them with her tail to scare them away. In The Dark Secret, Starflight thought that Viper seemed like the exact opposite of Sunny. She acted like she would rather die than stay on the NightWing Island. She was very strong and could get angered easily. She hated all of the NightWings.
In the prologue, Viper was fighting with her fellow false dragonets. Ochre, the MudWing, tripped over her, and she hissed and bit his tail. Squid said that she, Ochre, and Flame were bullies, with particular emphasis on Flame.
In the epilogue, they flew across the ocean with Morrowseer to the Night Kingdom and were placed in a cave. She told Ochre that he smelled bad, and she got angry with Fatespeaker when the latter claimed to be having another vision of the future.
Viper was introduced to Starflight, along with the rest of the false dragonets. She appeared to like the idea of replacing Fatespeaker with Starflight, preferring the true prophesized dragonet over their own version, but still tried to kill him on Morrowseer's orders. She stayed with Squid during the chase, and both of them were chased back to their cave by four NightWing guards. While Flame and Ochre were placed in the dungeon, she and Squid had to spend the night in the NightWing Dormitory. The NightWing dragonets annoyed her, and she threatened them with her tail before sulking in a corner.
The next day, Morrowseer took them to a remote SkyWing outpost and ordered them to convince the SkyWing soldiers inside to switch their allegiance from Burn to Blister. It ultimately was a failure, and they had to be rescued by NightWing soldiers. The soldiers then burned the outpost, killing the SkyWing soldiers in it. Later, she told Morrowseer that she would never do that again.
She was eager to jump into the practice fight with Fatespeaker. Viper blamed Fatespeaker for her being taken to the NightWing island, and nearly killed her before Starflight knocked into her. She lost her balance, then her tail sliced across Flame's face, leaving him scarred permanently, and she toppled into a river of lava by accident, resulting in her death. Starflight had tried to get Ochre, the false MudWing dragonet, to save her using his fireproof scales, but Ochre either didn't have fireproof scales, didn't know he had them, or simply didn't care, and he didn't even try to rescue Viper. Starflight then discovered that Morrowseer had been 'tinkering' with fate. When Viper didn't appear above the surface, Fatespeaker wept by the river of lava for the loss of her "friend".
Sunny and Tsunami tell the Talons of Peace of Viper's death, including a SandWing who is suggested to be her uncle or another extended relative as he asks about her, but doesn't seem torn or completely upset when Sunny says that she is dead.
In the epilogue, Fatespeaker said that Viper was one of the dragons "they cared about who had not survived the war".