Stonemover has gray and black scales that were the color of the desert sky at night time. His scales have partly turned to stone, including his back legs, his shoulders, and the edges of his wings, as well as his tail, which flops heavily along the ground behind him. The scales on his tail look like dark pebbles, sinking into the skin beneath. He has deep lines etched into his face, as if he is in pain, and he has black, unreadable eyes. His voice is deep, serious, and sounds dust-covered. His mouth almost doesn't move when he speaks. He is bigger than Thorn, but not as enormous as Morrowseer or Burn.
Moon notes that he looks weighted down. The stone across his scales makes him appear fossilized.
Thorn described him as being "always nervous, in a sweet, worried way." He never pretended to be scarier and meaner than he really was, and was described to be smart. He cared a lot for his tribe, to the point where he would give up something large for them. When Sunny met him many years later, however, she felt somewhat disappointed by his dull and depressing personality. When Moonwatcher met him in the caves, she remarked that he does not have much to say and think, lacking motivation to do most things. He often felt hopeless of his own future and gave up immediately when he felt his soul deteriorating, petrifying himself as a result instead of taking further action to solve the main problem. He is described by Moonwatcher to have very slow thoughts in addition to his slow, halting speech. Stonemover appears to not trust himself, saying his scales turned to stone for his own good. Moon and Sunny are both annoyed by his pessimistic attitude. He is also scared about ruining his soul and harming other dragons through animus power, which is why he turned himself to stone.
After the first eruption of the NightWings' volcano, Stonemover used his animus magic to create a series of tunnels. One connects the NightWing island to the Rainforest Kingdom as a passage for the NightWings to invade the rainforest, and the other connects the Kingdom of Sand (later used by the dragonets of destiny to meet Blaze) to the rainforest as a passage for Blister's SandWings to arrive with backup forces. It was here where he then met a young SandWing named Thorn. The two met in secrecy while Stonemover gathered the magic needed to create the tunnels, and over time they fell in love. However, Stonemover's animus curse began to take effect, and he left Thorn without her noticing or knowing about the curse. This prevented him from learning that they'd conceived a single egg. He made his way to Jade Mountain and managed to turn his animus magic against itself. This way, instead of losing his soul to insanity, his body would gradually turn to stone. He tried sending a message to Thorn to tell her how to find him, but the message was intercepted by Burn's army, and didn't reach her until the events of The Brightest Night.
Kestrel tells the dragonets and Peril that, if they ever needed her help, there was a dragon at Jade Mountain who could help locate her. This meant that Stonemover has somehow had some contact with the Talons of Peace and likely had an animus-touched item for locating them.
During the assault on Burn's stronghold, Sunny and Thorn discovered the message Stonemover had sent with his location. However, she was still mad at him for leaving and refused to seek him out. Instead, Sunny traveled to Jade Mountain to ask her father for help. He was at first amazed to learn he had a daughter, but quickly became somber after hearing Sunny's plan to end the war and find the Eye of Onyx. He also confirmed that the Dragonet Prophecy was written by Morrowseer and explained that no NightWing has had powers in over a century.
One month after Thorn was crowned queen of the SandWings, she finally came to Jade Mountain and was reunited with Stonemover.
When Moonwatcher, Sora, and Kinkajou were first visiting the Jade Mountain library, Kinkajou exclaimed that she heard of a ghost who lived in the academy. Starflight said that the ghost was really Stonemover, who would enjoy a polite conversation, which Kinkajou thought sounded boring. When Moon heard of this, she thought that maybe he was the voice in her head, which she later found out was wrong. She later visited and asked him about NightWing powers, but all Stonemover said was that they are long gone and that they'd ruin her life.
Stonemover is mentioned by Flame, who says that the animus refused to heal the scar on his face, left by Viper. However, after Darkstalker healed it for him, Flame tries and almost succeeds in killing Stonemover. Stonemover is saved by Darkstalker, who enchanted a stalactite to heal him and turned him back to a normal dragon. However, Stonemover started screaming that they weren't his talons, perhaps referencing that Darkstalker was taking control of him, and that his talons were monsters that should never be set free. Stonemover did not want his animus magic to do bad things to the world, so Darkstalker had to turn him back to the way he was. Stonemover is later shown at the end of the book with Darkstalker, Turtle, and Anemone, all of the animus dragons in Pyrrhia. Darkstalker asks him how many dragons were in that room since Turtle was hidden, and Stonemover replies "four," therefore giving away Turtle's presence.
While Qibli is searching for Ostrich, he blunders into Stonemover's cave. Stonemover is shown desperately trying to avert his eyes from Flame, who is trying to escape the prison Darkstalker made for him. Qibli notes that it is a worse punishment for Stonemover than for Flame before moving on.
Qibli also questions several times throughout the book that he thinks Flame may have been enchanted by Darkstalker to kill Stonemover, either to get rid of competition or to make himself look good.
Stonemover was indirectly mentioned by Tsunami when she was telling Sundew that they have four animus dragons. Stonemover also briefly appeared in Snowfall's vision as Jerboa III, when Jerboa III was brought into Darkstalker's throne room. She saw two SeaWings and a NightWing, Anemone, Turtle, and Stonemover.
"These aren't mine, […] No. No, I gave mine up. My talons are gone. These are monsters crawling out of the earth and they will rend the sky and crush the wings of small dragons and I can't let them I won't I won't I won't let them be used again!"
― panicking, after the healing spell took away his stone-scales curse. (Talons of Power, page 78-79)