He is a 12-year-old (when the series begins), kind, and caring boy who lives in Station Square on the planet Earth, which is regarded as an alternate version of Sonic's home planet in another dimension. At the start of the series, Chris finds Sonic at the bottom of his swimming pool and saves him from drowning, and hosts him, Tails, Amy, Cream, and Cheese for most of the series.
Chris lives with his grandfather Chuck Thorndyke (who is a scientist), his bodyguard and butler Mr. Tanaka, and his housemaid named Ella. He lives in a large mansion due to his parents being successful in their individual fields of work. Mr. Thorndyke, Chris' father, runs an electrical company and Mrs. Thorndyke, Chris' mother, is an actress. As a kid, Chris rarely saw his parents, which made him become very lonely to the point where he feels threatened by abandonment when Sonic and the rest of Chris' friends return to their world, even though it wasn't their fault that they had to leave. His uncle, known as Sam Speed, is the head of a police car-chase team, drives a Formula One race car, and has some sort of rivalry with Sonic. Chris' elementary school teacher is Mr. Stewart, who turns out to be a spy working for the government later in the show.
At the end of the 2nd season and during the 3rd season, Chris becomes 18 years old. Early in the third season, he uses a portal to travel to Sonic's home in the show. After this point in this series, Chris is still in his preteen design and still speaks and thinks in his younger voice due to the passage of time being different in Sonic's dimension. Yet, he has the memories of the past 6 years of his life, prior to traveling to Sonic's world. However, he has gained new skills during the 6 years in between the show. The new Chris no longer takes the backseat in the X-Tornado; instead, he's shown as flying it capably, which his younger self would've never picked up. Chris also comments in one episode that he is a black belt in Karate. Additionally, he has also shown to have become a quite capable engineer, enough to impress the super-smart Tails. He invents different gadgets and devices like Sonic's Hovershoes, a hoverboard, and a new, better Chaos Emerald scanner for the Blue Typhoon. He is also seen in a few episodes using Flash Bombs as a distraction and he also uses a laser gun as a weapon.
Sonic the HedgehogEdit
Chris first met Sonic when he crash-landed into the swimming pool of the Undertale mansion, and at first, he had to keep the fact that he saved a blue, talking hedghog a secret. Unfortunately for Chris, his grandpa Chuck discovers Sonic and suspects that he is a robot. However, he later proves instrumental in helping to rescue Sonic's friends and finding the Chaos Emeralds. Sonic and Chris quickly form a close bond that turns into an everlasting friendship. Like Tails, Chris is as close to Sonic as a younger brother would be.
Miles "Tails" PowerEdit
Chris and Tails are good friends throughout the first two seasons and are seen riding in the X Tornado together. Chris helps Tails give Sonic Power Rings when Tails is too busy to.
Amy Rose is another one of Chris's friends, the two get along quite nicely.
Knuckles the EnchindaEdit
Not much can be said about Chris's relationship with Knuckles except that the two get along well enough. After Chris gets captured by Eggman due to Knuckles believing his lies (again) in episode 25, Knuckles makes it his prerogative to find and rescue Chris. (Although it's Rouge the Bat who does so.) Throughout the series Knuckles is shown to be concerned for Chris's safety such as in episode 45 when they entered a fighting tournament, Knuckles refused to fight Chris because he did not want him getting hurt.
Cream the RabbitEdit
Cream is also one of Chris's friends, they are seen tagging along together in some episodes. Cream gets mad at Chris in episode 7 after he makes a comment about how his mom is rude to leave the party without telling the guests. Cream is upset because she overheard his mom crying about how she is never able to be there for him and that Cream can't see her mom since she is back on Sonic's world. Later Cream forgives Chris and makes him a crown of flowers which according to Sonic is something that she only does for people she really likes.
Cosmo the SeedrianEdit
Cosmo is a friend of Chris as well, they get along pretty well. Cosmo starts looks up to Chris after he nearly succeeded in rescuing her from Black Narcissus during which time Chris tells Cosmo that she reminds him a lot of himself before he met Sonic. Like the others, Chris is greatly saddened when Cosmo sacrifices herself to save the Galaxy.
Chris and Helen are very close friends; in the first two seasons of the anime, Helen is the most trusted human friend of Chris. In the second season Helen and Chris have become boyfriend and girlfriend and they both excel at machinery.
Danny is one of Chris' closest friends, they are seen hanging out together throughout the series and help each other and Sonic and Friends throughout the series.
Frances is another close friend of Chris who helps Sonic and team out in the first season. Frances is seen as a tomboy and enjoys poking fun at Chris and Danny.
Shadow the HedgehogEdit
Chris takes an interest in Shadow especially when he returns after supposedly sacrificing himself to stop the ARK from hurtling into the earth. Shadow does try to hurt Chris at one point, but Chris is rescued by Rouge, who later abandons him and then Chris must be rescued by Knuckles. Although at times Chris has shown signs of dislike for Shadow, he has also shown signs of liking him. Chris kept Shadow's rings until Shadow came back and Chris returned them to him. Chris did shed one tear when he learned Shadow was supposedly dead. Chris also convinced Shadow that Maria would want him to help people before Shadow lost his memory.
Chris is sometimes criticized for his roles in the Sonic Adventure adaptions as he takes the place of the other characters that had an important role in the games. For example, during the adaptation of Sonic Adventure, he journeys with Big and Cream as they go looking for Froggy (even though it should be noted that Cream has never gotten any criticism for usurping Tails' role in finding Froggy). In the anime's version of Sonic Adventure 2, he replaces Amy as the one who convinces Shadow to save Earth. He also receives Shadow's ring as Rouge did in that game. He's also been often criticized for taking many roles from Tails due to their similar personalities and being Sonic's new best friend throughout the show. He has also been criticized for other reasons, such as having arguably more screen time than Sonic and shutting down the portal so Sonic couldn't return back home. But in the end of the 2nd season, Chris let Sonic return to his own world. In the 3rd season, Chris returns and reunites with Sonic and his friends. He joins Sonic and his friends to help Cosmo defeat the Metarex. When the Metarex was destroyed, Cosmo sacrificed herself to save her friends and the galaxy. And in the end of the 3rd season, Doctor Eggman revived his rivalry with Sonic, now that Chris is out of the way.
- Chris was designed and created by Tetsuta Nomura, famed designer and artist responsible for famous characters such as Sora from the Kingdom Hearts series.
- Chris was one of four Sonic X characters exclusively promoted by Sonic Team (the others being Danny, Nazo, and Cosmo), and one of only two characters promoted by 4Kids Entertainment (along with Chris' grandfather Chuck Thorndyke).
- While never physically appearing in the video games, Chris does appear on a poster for Sonic X next to Sonic in the Mission Mode of Sonic Adventure DX. His voice is also heard congratulating Sonic whenever Sonic solves a problem in the Sonic X Leapster game.
- He invented 5 pairs of shoes for Sonic on Season 3, one of which appeared to be Sonic's Soap shoes from Sonic Adventure 2.
- He also appears as a main character in the Sonic X comic.
- Chris reminds Shadow of Maria because of their caring personalities and the similar look in their eyes.
- Chris making it home safely at the end of the series is never confirmed, only heavily implied by Eggman.
- Even though he only appears in Sonic X (minus the Leapster game), Chris was created by Sonic Team. He also appeared with Sonic in the most episodes of Sonic X (76).