Preston is a stuck-up rich boy who is shown to love and care about his dog, Jacques more than he does about anyone else. When giving Jacques a command, he speaks French with a rusty, nerdy, and annoying accent. As two-time champion, he takes pleasure into bullying Calvin and mocking his dog, Tyco, whom he despises to no end. No matter what Jacques does to others, he does not seem to care like during that scene where Jacques attacked Calvin while he was skateboarding and Preston seemed to think that it was Calvin who hurt Jacques instead while pampering and tending to Jacques.
As a rival, he would do anything to make sure his dog wins the dog show; even if it means cheating like hiring and paying people to beat Calvin up and later, others to pretend that they are Tyco's real family or even sabotaging one of the dog obstacle courses during the show. He is selfish, greedy, jealous, stuck-up, snooty, snotty, snobbish, obnoxious, bratty, bullying, scheming, careless, sneaky, arrogant, sleazy, cruel, and mean.
Role in the film
Preston has taught his two-time champion dog, Jean-Jacques Saint-Germaine de Dupree a.k.a. Jacques some new tricks, which he performs perfectly well at his command in French before a basketball match at Bedford High begins; thinking his dog's performance will inspire everyone to be champions, including the school's Wildcats; much to the bore of the players and other students.
After the Wildcats win, one of the players, Rondel thanks everyone for their support and dedicates it all to "a very, very special fan." Preston, thinking it's him, tries to thank everyone and speak when in fact, Rondel meant his friend, Calvin Wheeler, whom without his help never could have won the game; much to Preston's jealousy and dismay.
The next day, Preston is seen bossing some workers around about where to put his new fountain in his yard next to his mansion while scolding and insulting them about their "incompetence"; thinking his dog needs more space for training and exercise, when Jacques, all of sudden, runs and attacks Calvin, who is minding his own business while skateboarding. Nevertheless, Preston wastes no time tending to Calvin when in fact, he pampers and tends to Jacques; thinking it was Calvin who hurt Jacques instead. When Calvin recuperates and tells Preston off with the truth, Preston refuses to listen and gives him an uninteresting lecture and education about himself and his dog. When Preston mentions the 1st prize for winning a dog show at the Bedford Civic, in which the next one is in two weeks from now, is $5,000, it interests Calvin; knowing he can use $3,000 from it to buy the first issue magazine of Gotham Man to finally complete his collection.
A few days later, after Calvin gets a Labrador/Saint Bernard hybrid from the pound named Tyco, Preston mocks Calvin and Tyco and threatens to "destroy" them at the dog show; thinking that "dog shows are out of Calvin's league." Then, he warns Calvin "to drop whatever scheme he's planning with Tyco." Luckily, Tyco comes to Calvin's defense by going around Preston, having him tied and stranded to his leash, and then, dragging him in the mud. Calvin and Raymond Figg try to get Tyco to stop but to no avail. Even Preston calls for his dog's help but it doesn't work either.
Then, Preston pays a couple of guys (and somewhat "friends" of Calvin) named Leonard and Thrash to beat Calvin up to make him and Tyco stay away from the dog show and encourage him to drop out even if Calvin promises to take Tyco back to the pound after school; especially after all the trouble and mess he caused in the house the other day, until Tyco breaks free from and with the tree he is tied to on a leash, breaks through the fence, and rescues Calvin from the two would-be trouble makers. This rescue later changes Calvin's mind about the pound and allows Tyco to stay (as long as his parents aren't still aware).
The next day, at the Royal Hound's Obedience and Obstacle Dog trial, seeing that Calvin is still in one piece and with his dog and Figg, Preston tries to get them nearly kicked out due to Tyco not being properly groomed as he sarcastically wishes them "good luck" until Calvin calls up Rondel, his teammates and his mother, who is a Beauty Salon hair dresser, to take care of Tyco's grooming.
At the trial, both competitors compete with their dogs through the obstacle courses with Preston losing control of Jacques and despite Tyco having caused a bit of a mess and a few time penalties, Calvin and Tyco are declared the winners with Tyco earning the nickname "Tyco the Terrible" and making it to the Top-Dog finals. Preston tries to angrily protest when believing it to be unfair and accusing Tyco of cheating, but everyone ignores him. When Preston thinks that he and his dog will be impossible to beat according to a lady reporter during a small press conference, Calvin simply replies with his famous motto: "Expect the impossible."
As a way to exact his revenge for his humiliating defeat, Preston posts fake posters of Tyco on the streets; claiming he's "a lost dog named Chester already belonging to a family", thus, forcing Calvin to give up Tyco to his "family" until the jig is up when Calvin's girlfriend Emily Watson discovers the photo to match exactly like the one she took when Tyco was first brought into the shelter, thanks to Figg. When they tell Calvin the truth, he finally realizes it was Preston behind the plot and that Tyco's so-called "family" were actually a couple of people he hired and paid them to pretend that they were his real "family".
On the following day of the Royal Hound Top-Dog finals, after Calvin and his friends manage to get Tyco back, and Preston and his dog have finished their routine and score a 98, Preston is shocked and surprised to find Calvin and Tyco back just in time before their disqualifications. He even tells them that it'll be impossible for them to beat his score, but Calvin refuses to listen and continues anyway. Seeing as to how incredibly well they are performing, Preston, worried that Calvin will win and refusing to admit defeat, takes Jacques and decides to take matters into his own hands by sabotaging one of the dog obstacle courses during the show, which collapses on them. Nevertheless, Calvin and Tyco still win, beat Preston's score by one point, and get a 99/100, and Preston gets disqualified for the sabotaging.
Along with using that reward money to buy the last comic book, Calvin uses the money for good. He gives the money to the shelter (where Tyco used to be) so that the dogs can have better homes. In the end, the shelter is saved and Figg along with many other people adopt a new pet.
His fate is unknown when he & Jacque were smothered in the collapse.