Originally from rural Louisiana, Thornton's family life always revolved around horses. His father was a quarterhorse and thoroughbred trainer, a blacksmith who made horseshoes and an equine dentist. As a teen, Thornton even rode bulls at rodeos.
"Horses and animals have been my whole family's life. So it's in my blood," he said.
Don't mistake Thornton's cool-dude looks and casual demeanor for complacency, however. The 24-year-old has earned lead rider status at Hawthorne since 2008 and has won over 1,000 races and made more than $22 million for horse owners during a nine-year career, despite a spate of injuries.
His most recent major accident came in October, when his horse fell during a race and one of his competitors accidentally ran him over. The result: a broken cheekbone, eye socket, collarbone and ribs, causing him to miss five weeks. Thornton's biggest regret? That he wasn't on Peyote Patty's back when his favorite racehorse won the final event of her career.
"I'd got on her as a baby and we had five years together and we'd had so much success," said Thornton. "The fact that for her farewell race she had another jockey on her? I can't lie, I might have cried a little about that."
Slinger tries not to think about her injuries, although sometimes she can't help it. There are times when she wakes up in the morning and feels the aches and pains of previous accidents and ailments.
"Sometimes I feel like an old person around the house, holding my hip or whatever," she said.
In 2009, she broke her face—meaning she fell in a race and suffered an orbital fracture that had to be reset. Most recently, Slinger cartwheeled and hit her head, causing a mild concussion after being catapulted off her steed.
"Some of us, for some reason, are less lucky," Slinger said with a shrug. "Brandon is on the same trajectory; we break everything."
IN HIS FATHER'S FOOTSTEPS
Brandon's father, Randy Meier, tried to stop his son from following in his footsteps. Randy reigns as the all-time leading jockey at Hawthorne and the now-defunct Sportsman's Park (demolished in 2009), but nearly three decades immersed in horse racing took a major toll on both his body and his relationships.
"My parents were together 27 years, but he kept saying he was going to retire and never did, so my mom left him," Brandon said.
Despite his son's interest in the sport, Randy asked him to attend at least one year of college before taking up the reins as a rider.
"I want you to use your brain, not your back," Randy told Brandon.
The younger Meier kept up his end of the bargain by attending two semesters of school, but no more.
"I went and partied my ass off and slept with as many girls as I could, but then the spring came and I wanted to ride," said Brandon.
Father and son spent two years as a popular tandem on the track before Randy was forced to retire after suffering a fractured neck (the second of his career) and brain damage in a shocking accident at Hawthorne that nearly killed him.
Over the next several months, Brandon would help take his father to a rehab hospital in Wheaton for physical rehab and speech therapy. But despite seeing the horrific extent of his father's injuries—which included 55 broken bones and 13 concussions—Brandon refuses to give up his career, even now that he's amassing his own laundry list of ailments.
In his five years as a professional jockey, he's torn his right shoulder, suffered a collapsed lung, broken his wrist several times and lacerated his liver. He points to a 6-inch scar down his clavicle. Underneath the skin is a surgically installed plate with eight screws holding it in place. Meier seems less concerned about the injury itself and more upset at the possibility that the metal in his body might be weighing him down a few ounces before he stands on the scale.
"Every little bit matters," he said.