When Thorne was eight, he freed a rare Sumatran tiger from the Los Angeles Zoo. Thorne was on a field trip with his class at the time and he opened the cage. Thorne explained to the authorities that the tiger "looked sad locked up like that, and that he didn't regret it." At eleven, Thorne's parents filed a police report stating they had been robbed of a second-era diamond necklace that belonged to Thorne's mother. Thorne later sold the necklace on the net for 40,000 univs to a person in Brazil. However, he was too late in sending the necklace and was forced to return the payment, along with an apology. Thorne claimed that "he was only trying to raise money for a local charity offering android assistance to the elderly." At thirteen, Thorne was given a week-long school suspension after losing in a fight to three boys in his grade. Thorne said that "one of the boys had stolen a portscreen from a girl named Kate Fallow" and that he "had been trying to get it back."
When Thorne turned seventeen, he was accepted into the American Republic military. When he was nineteen, he removed his ID chip, stole a spaceship, the Rampion, and deserted the military. Eighteen months later, Thorne was found and arrested in the Eastern Commonwealth. Although he was a criminal, many Earthen girls swooned and gossiped about Thorne, and he became a celebrity. Cress eventually fell for him when she was looking for Linh Cinder from her satellite. She explained how she felt like she had a certain connection to him and that he would be her hero. She too thought that he is very handsome.
On the 228th day of Thorne's captivity, Cinder drilled a hole through his prison cell's ceiling. Cinder muttered that she was one room off. Thorne attempted to flirt with Cinder, but she repeatedly brushed him off and found him more annoying than charming. She took his vid-cable from his portscreen as hers was "on the fritz." Thorne offered to be her accomplice and mentioned that he had a spaceship. As she drilled another hole, Cinder unknowingly glamoured Thorne into adoration and compliance by telling him to "stop talking" in thought. Cinder, needing a way out of New Beijing, took Thorne with her on her escape in order to use his ship.
When they reached the hanger that held his spaceship, they met up with the owner of the hanger who seemed to be good friends with Thorne, but would not help them because Cinder was a Lunar. Cinder glamoured him until he blacked out and the two took off in Thorne's spaceship, nearly getting captured by the police. After being in space for awhile, they landed in Rieux, France in order to look for Michelle Benoit. Thorne believed that the Lunar princess was still alive (Cinder had not told him that she was Princess Selene yet) and was happy to help. When they reached Michelle Benoit's house, they found it ransacked and went into the room that Cinder was held in for eight years. Thorne showed obvious sympathy and horror at the sight of Cinder's mutilated three-year-old body, unaware he was looking at a younger Cinder.
Thorne and Cinder tracked down with Scarlet Benoit and Wolf while trying to find Michelle Benoit. Cinder, needing a real pilot and more allies, accepted Scarlet and Wolf onto her ship. There were then four people on Thorne's ship (excluding Iko): Throne, Cinder, Scarlet, and Wolf.
Thorne is described by Cinder as having a "square-jaw, bright-blue-eyes, devilish-dimples." He is noted to have a bit of stubble when he was in prison, and when he was lost in the desert with Cress. On Twitter, Marissa Meyer confirmed that Thorne had brown hair.
Thorne is seen as sarcastic, has a devious streak, and is egotistical. In the beginning of Cress, Cress had thought of him as "princely" and kind. That thought is later proved wrong, as he is within the range of kindness when it comes to Cress.
"Carswell" is a relatively uncommon given name that means "watercress spring," deriving from the surname of the same spelling.
The surname "Thorne", pronounced the same as "thorn", probably comes from the fact that in the original telling, when the prince finds the witch in the tower instead of Rapunzel, he is pushed out and falls into a bed of thorns.
At first, she was disgusted by him and his apparent greed and recklessness... [But] like the sun rising over Earth's horizon, her perception began to change. Carswell Thorne wasn't a heartless scoundrel at all. If anyone bothered to get to know him, they would see that he was compassionate and chivalrous. He was exactly the kind of hero Cress had been dreaming about her entire life.
Thorne and Cress first met via comm. Cress was tongue-tied and self-conscious, worrying about her appearance. Thorne expressed bewilderment at her vast amount of hair, quoting; "Aces...is all that hair?" His first line is thought to have parodied Flynn Rider's bafflement at Rapunzel's hair in the Disney animation, Tangled; "Is this...hair?"
They first met face-to-face in a podship, both of them tied up and gagged.