Getty Images

Even at two months old, the vibe Casey Thompson gave his father was one of a quarterback in the making. Charles had been a significant one at Oklahoma in the late 1980s.

"[My father] always says, 'You'll never be me. I'm way better than you were,'" Casey said this week ahead of Saturday's rivalry game between No. 21 Texas and No. 6 Oklahoma.

If that debate were only about football.

While Casey, Texas' junior quarterback, is in the early stages of building his legacy, part of his father's has been cemented long ago.

In 1989, Charles Thompson was busted by the FBI for selling $1,400 worth of cocaine to an undercover agent. He appeared on the cover of Sports Illustrated, handcuffed and wearing an orange jumpsuit.

"One week, Charles is over at my house playing Nintendo with my son. The next week, he's on the cover of Sports Illustrated. He paid a severe price for it," said Jim Donnan, Charles' offensive coordinator at Oklahoma.

A few months later, coach Barry Switzer, his program awash in scandal, resigned.

Charles Thompson spent 17 months in a Texas federal prison. Devastated by wrongdoing and NCAA probation, Oklahoma spent a decade off the national radar before being rescued by coach Bob Stoops.

Enter Casey, making his fourth career start for the Longhorns on Saturday at the Cotton Bowl.

Since Stoops arrived at the turn of the century, the Red River Showdown has been defined by quarterback play. Four Heisman Trophy-winning QBs (all of them from OU) have played in the game since 2000. That doesn't include Josh Heupel, who was a close runner-up that year.

Casey is not a Heisman candidate nor a significant figure in the rivalry. Yet. But just getting to this point has been a journey.

Oklahoma established itself as a national power recruiting Texas going back to the Bud Wilkinson days. Texas crossing the Red River to land a skill player is more of a rarity. Thompson is the only Oklahoman currently listed on the Longhorns' roster.

"It's an interesting story," Donnan said. "An OU quarterback's son playing for Texas. Are you kidding me?"

Legacies are always at stake in Red River. This one is unique.

Despite being time-stamped with that arrest, Charles long ago cleaned up his life. He is a successful businessman, motivational speaker and doting father.

Charles Thompson running the option in the 1988 Orange Bowl. Getty Images

As far as that trash talk with his son, Charles' on-field accomplishments back it up. He is still remembered as the star quarterback who led Oklahoma into a 1987 national championship Orange Bowl matchup against Miami. (The Sooners lost 20-14.)

"Sometimes in the offseason, when I'm bored, I'll turn on a game and watch start to finish," Casey said. "I'll write down throws and say, 'You missed this throw. You missed this read.'"

Dad will counter by saying he would have scored "100 touchdowns" in today's wide-open offenses.

Charles also beat Texas twice, which brings us back to this week. Casey grew up in the Oklahoma City area rooting for Oklahoma. On Saturday, he'll try to beat the Sooners in a rivalry that is marked by opposing fans literally sitting across from each other in the Cotton Bowl, the aisle on the 50-yard line separating them.

"When I was in high school, when I was getting recruited, some of my teachers and best friends were like, 'I'll never root for you. I'll never cheer for you,'" Casey said. "… I never really grew up hating Texas. I've never been like that, and even now at Texas, I don't hate OU. I just try to focus on doing my job, and at the end of the day, I'm a competitor.

"I want to win, and I also want to start."

That starting spot is one of the significant storylines of 2021. Casey, who turned 23 on Sunday, has been on campus for more than 3 ½ years since being signed by former coach Tom Herman. He will make that fourth career start Saturday having taken over the job from Hudson Card last month.

Texas got a jolt from his insertion on Sept. 11 at Arkansas. With his legs, Casey gives the 'Horns that plus-one advantage of a mobile quarterback. With his arm, he is the Big 12's most efficient passer. Only Oklahoma's Spencer Rattler has thrown more touchdown passes.

Casey came to Texas in January 2018 knowing full well Sam Ehlinger was on campus. He threw only 29 career passes before this season, somehow deciding not to transfer in this age of impatience.

"Why in the world had he not gotten a chance to do anything the last 2 ½ years?" Charles Thompson told 247Sports earlier this year. "The assumption is he was not any good."

Casey's first meaningful snaps came in last year's Alamo Bowl. Ehlinger was out at halftime against Colorado with a sore shoulder. In came Casey, who threw five second-half touchdowns. That night, he became the first player in 20 years to throw at least four touchdowns over 10 or fewer pass attempts in a bowl game.

It was assumed he had the advantage coming into 2021's quarterback battle. Casey played the role of starter, flying the Texas starting receivers to Miami in the offseason to train and work with NFL veterans Stefon Diggs and Jarvis Landry. (Don't ask how Casey was able to afford that trip. He did not elaborate.)

But Card won the job out of camp, and a lot of folks still can't figure out why. There was speculation Texas coach Steve Sarkisian was worried about the redshirt freshman transferring.

Casey already had proved his loyalty. Once he committed, Oklahoma, Alabama, Georgia and Ole Miss "came knocking at the door." He did not budge.

"Once I committed to Texas, I didn't want to deal with it anymore," Casey said.

"He wanted to be a Longhorn through the adversity, through being the backup, through not being named the starter, through that perseverance," Sarkisian said.

Casey continues to prove that loyalty, taking the offensive line out last week to Vince Young Steakhouse. That outing wasn't cheap, either.

"It's something I did out of my pocket," Casey said. "I'm not going to let them take advantage of my pocket."

Whether he wants to admit it, there's another legacy at stake going forward: Casey becoming the highest-achieving Thompson.

Dad won Big Eight titles and played for a national championship but spent the back end of his eligibility in jail.

Older brother Kendall played quarterback at Oklahoma and Utah but seldom saw the field.

Younger brother Cade is still at the beginning of his career as a tight end at Southmoore High School in Moore, Oklahoma.

"I try not to focus on it being about me," Casey said. "I'm from Oklahoma and play for Texas. That alone is unique."