When he talks about his concussions, Dale Jr. has a hard time keeping them straight. They're variations on the same horror story.

In 1998, racing at Daytona in the Busch series, he collided with Dick Trickle and went airborne backward. His car barrel-rolled and bounced off Trickle's hood before landing, somehow, upright. When he got out and tried to do an interview, he fell down. Later on, his crew noticed that the wreck had thrown him sideways so hard that he had bent the door with his helmet. They all laughed about it.

In 2002, at the Napa Auto Parts 500, he got tangled with Kevin Harvick as Harvick dove for pit road. He went headfirst into the wall in nearly the same way Dale Sr. had done the year before. He hid his symptoms from his team and drove with a concussion for three months afterward. When NASCAR found out, it put in a new rule giving doctors at the track more authority to demand concussion tests after a wreck.

In 2012, during a test at Kansas Speedway, one of his tires blew out and he went straight into a fence at 190 mph. The moment just before he hit was the one time he thought he was going to die. He felt sick at dinner afterward, but he had seats in the owner's suite to a Washington Redskins game that night -- he's a lifelong fan -- so he and Amy went ahead and flew to DC. Now, when he thinks about it, the whole day feels like a hallucination.

Six weeks after that, he got trapped in a four-wide pack on the last lap at Talladega and got hit from both sides in a massive wreck involving 25 cars. Steve Letarte, his crew chief at the time, called him on the radio: You OK, buddy? Dale Jr. replied: I don't know, man. I mean, I don't know how many of them hits like that I can take. Doctors concluded that he'd had two concussions: one from that crash and one from the wreck in Kansas. NASCAR ordered him to sit out the next two races. That was the first time he rehabbed with Dr. Collins.

Those are just the concussions he's sure about. Like every other professional driver, he has wrecked dozens of times -- all the way back to when he was a teenager, fiddling with his new CD player, and flipped his Chevy truck on Christmas morning. His career is a timeline of concussion awareness in sports. In '98, laugh it off. In '02, keep driving. In '12, miss a couple of races. In '16, sit out half a season.

NASCAR, like other sports leagues, is trying to keep up. In 2014, it started requiring baseline concussion tests for drivers before each season. The ImPACT test measures short-term memory, reaction time, attention span and problem-solving. Drivers who wreck take the test again, and doctors compare the results to check for impaired brain function. (Some scientists question whether the ImPACT test really works, and some researchers are concerned that it frequently shows false positives. Still, sports teams and leagues around the world use it, including teams in the NFL, the NHL and MLB and in collegiate and high school sports.)

The nature of racing presents problems other sports don't have. After a big wreck, it's easy to check a driver who has to get out of a crumpled car. But what if the car can still go? Drivers steer bent-up cars back onto the track all the time -- the longer they stay in the race, and the higher they finish, the more they get paid. Doctors can't check a driver who doesn't pull over. And if NASCAR changed the rules to park any car involved in a crash, drivers -- and fans -- would be furious.

Drivers on the IndyCar open-wheel circuit wear earpieces that measure the forces on a driver's brain in a crash and send the information to an impact data recorder -- a "black box" -- that's installed in every car. Officials study the data and, based on their guidelines, can force a driver to sit out at least the next week. NASCAR cars have had black boxes since 2002, the year after Dale Sr.'s death pushed the sport to make cars and tracks safer. But drivers don't have the earpieces, so NASCAR can't tell with any precision how a crash directly impacts a driver's head. And, at least officially, NASCAR doesn't use the crash data to decide whether a driver should sit out a race.

Still, NASCAR drivers are paying attention. Carl Edwards nearly won the Cup championship last year before wrecking at Homestead-Miami with 10 laps to go. But in January he announced that he was stepping away from the sport at age 37 and mentioned Dale Jr.'s concussions as a factor in his decision. "I don't like how it feels to take the hits that we take," Edwards said. "I'm a sharp guy, and I want to be a sharp guy in 30 years."

The major problem in racing is a theory of relativity. The long-term risks of concussions are now clear to most athletes. But race car drivers risk much worse every time they pull onto the track. No one knows that better than the son of Dale Earnhardt.

Back in November, when Dale Jr. was doing one of those Homestead-Miami meet-and-greets, he talked about how the race there doesn't start until midafternoon. That means that midway through the race, the sun sets straight into the drivers' eyes. For half an hour, on every lap, the drivers come out of Turn 4 and for a few seconds their windshields turn white with glare. They can't see 15 feet in front of them. "Like flying through a cloud in a plane," he said.

Imagine being behind the wheel with 40 drivers on the track, all going 130 mph, all basically driving blind. Later on, I ask Dale Jr. about it: Doesn't that scare the crap out of you? He shrugs. He's got a spotter to tell him what he can't see. He trusts the other drivers. It doesn't last that long. All of which is to say: His nightmares are different from yours and mine.

Now we're in Las Vegas for the NASCAR banquet, a week before the test at Darlington. Dale Jr. and Amy sit down to lunch at a restaurant in the Wynn hotel. The server brings by a tray of red velvet cake macarons. Dale Jr. has never had a macaron. "Holy moly," he says.

Back in the summer, after the concussion, Vegas would have felt like hell. Five weeks into recovery, nothing was getting better. His eyes still shook so bad he couldn't focus. He stumbled in the aisle at Sam's Club. His face clouded over and he got extra quiet -- the surest sign he was in a bad mood.

The people close to him cared about his recovery as a person but also as a driver, because with Dale Jr. it is all mixed together. Kelley runs JR Motorsports, which handles his marketing and fields a team of drivers in the sub-Cup circuits. His mom works there in accounting. Rick Hendrick -- owner of Hendrick Motorsports, the team Dale Jr. drives for -- has known Dale Jr. since he was a child. Three years after Dale Sr. died, a Hendrick Motorsports plane crashed in Virginia. One of the 10 people who died was Ricky Hendrick, Rick's only son. In some ways, Hendrick says, he and Dale Jr. have been parent and child for each other ever since: "I've kind of filled the role in his life, and he's filled a little of that role in my life."

(The one family member Dale Jr. doesn't spend time with is his stepmother, Teresa Earnhardt. They separated professionally in 2007 when Dale Jr. left Dale Earnhardt Inc. -- which Teresa ran -- to race for Hendrick. They haven't had much contact since.)

Every morning that Dale Jr. woke up and lost his balance was another morning that millions of dollars in decisions had to wait. Sponsors were already making plans for 2017 and wondered whether he was coming back. His team didn't know from week to week whether he'd be driving the car.

He tried to speed up his treatment, but it was like he was stuck in sand. Collins prescribed a mild anti-anxiety drug. He put the word out to Dale Jr.'s family and team: Don't keep checking on him. Don't even ask how he's doing. Give him some space for a while.

The only one who saw him every day was Amy.

They met in the fall of 2008, when he decided to tear down his old house and build a new one. She was an interior designer for the team he hired to do the work. Dale Jr. talked T.J. Majors, his spotter and one of his best friends, into tagging along to the meetings about the house. You have to see this girl, Dale Jr. said. T.J. watched them look at each other across the table.

It wasn't an easy beginning. Amy had been married and split from her husband. Dale Jr. had been with lots of women, but he'd never learned how to treat one.

He'd call his buddies, and they'd call their buddies, and there'd be 100 people at the house before Amy knew what was going on. "When me and Amy first met, I was super selfish," he says. "We're doing whatever I want to do. You wanna do what I wanna do, right? Yeah, we're doing it."

Amy wondered why she had moved to North Carolina. They had multiple come-to-Jesus moments, but none stuck. Dale Jr. was still determined not to grow up. He stayed up all night playing video games. His friends brought him takeout for supper. But every so often the kind side of him would come out, the side that wanted to make her happy. It was just enough to hang on to. She stayed. And slowly, Dale Jr. realized he wanted her to.

"I don't know what the turning point was," Amy says.

"I do," Dale Jr. says. "In my heart and mind, it's always been Jane."

Jane is their couples therapist. They've been seeing her for three years. It was Dale Jr.'s idea. He has been in counseling of one sort or another, off and on, since he was 11 or 12. He also has seen it work for other family members. Jane was the one who helped him understand that he was committed to the wrong things, that he was worthy of a better life.

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Looking back, he sees what a jerk he was -- to Amy, to his crew, to anybody who tried to get him to do anything besides what he wanted to do. Part of it was his anxiety, which led him to cut relationships short before they went bad. Part of it was the entitlement of being a millionaire when he barely needed to shave. Part of it was the worry about being discovered as a fraud who didn't deserve any of it.

And part of it, he knows, traces to his childhood, to the little boy playing with Matchbox cars while his dad was gone racing real ones. Dale Jr. is not ready to dig quite that deep yet. He just knows he spent years going in the wrong direction.

"I ran that course for so long," he says. "Too long. I had had enough. But I didn't know how to be a good person."

For Amy, he learned. He started listening. He kept more regular hours. When they built the new house, they redid the basement. It's still spectacular -- a theater, a karaoke rig, an old Chevy truck they turned into a DJ booth. But these days Dale Jr. is more likely to listen to old LPs down there while Amy has a glass of wine. It's not Club E anymore.

After the concussion, Amy woke him up every morning to do his rehab work. He shot baskets and flung medicine balls. He did elaborate vision drills -- reading a tiny eye chart he held out in front of him while he walked forward and backward, shaking his head back and forth. He stumbled around in a dark room with swirling lights so his body could learn to get its bearings again. Nearly two months into rehab, he finally started to get better. His stress level dropped. And as it did, he noticed he had become a different man.

He came back to his race shop to hang out with his crew, and over sushi at a place down the road, they bonded again. He jumped back onto the team message board, where they share race info and give one another unrelenting grief. The crew members had been able to tell, just from his body language, when they needed to take the long way around him. Now he walked lighter.

For years, Dale Jr. had mapped out his life to the hour -- he clung to routines because new things made him anxious. But now he had free time and a desire to improvise. He and Amy took a last-minute trip to Texas to see her parents. They flew to a music festival in Milwaukee just to see a band they loved, Lord Huron; Dale Jr. stood in the crowd, anonymous.

Back home they went to the Cabarrus County Fair with Greg Ives -- his crew chief since 2015 -- and Ives' wife, Jessica. They went down to watch the pig races. Dale Jr. walked down the midway, a version of that dark rehab room with the swirling lights. This time he didn't stumble.

He even tried a few rides. He and Amy climbed into one that was a version of the classic Gravitron -- you get into a big cylinder, stand with your back against the wall and hang on as it starts to spin. The force of the spin presses you backward. You feel like the world is about to drop out from under you.

Amy almost threw up. Dale Jr. was wobbly when it was over. But they survived the ride together.

Dale Jr. puts his head in his hands: "I am so sick of talking about myself."

Some of the old Dale Jr. has returned this afternoon, mid-December, a week after Darlington. We're at his and Amy's house, which he doesn't like to show to strangers. He got here late because another appointment ran over. He has to pose for photographs. He's being polite. But normally he talks in paragraphs. Now everything he says is two or three words.

He's down on himself today too. Racing is not that hard, he says. Most anybody could do it. The walk back to the motor coach at Bristol wears him out more than the race.

Dale Jr. has lived his complications in public while he agonized over every one in private. This couch we're sitting on is where he and Amy curl up with Gus, their Irish setter, and laugh at Junebug, their Pomeranian. The bedroom upstairs is where he can't sleep unless he drapes himself over Amy.

This is a place for family. We're not family.

He perks up once. I mention all the odd things he has collected on his 200 acres. There's an Old West town, a replica gas station, a custom treehouse, a six-hole pitch-and-putt golf course. Strewn through the woods are carcasses of old race cars he has collected for years. I mention how weird it will be when somebody digs this place up 10,000 years from now.

"That's right," he says. "I want people to wonder what happened here."

History matters to him. He still has the Redskins helmets and uniforms his mom gave him for Christmas when he was a kid. He has a private server with recordings of hundreds of NASCAR races going back to the '50s. He proposed to Amy at a church in Germany, in the town where he had traced the Earnhardt family back 10 generations.

While the photographer works, I wander into a hallway off the living room and find a little museum of history: the history of Dale Jr. and his dad. Here are two of Dale Sr.'s firesuits. There's his application to race in NASCAR. Follow the pictures down the wall and you see Dale Jr. turn from boy to teenager to grown man with Dale Sr. by his side. Dale Jr. didn't used to keep many pictures of his daddy around. But that was before Daytona in 2001.

And now we're back to that moment.

Dale Sr. was running third when he hit the wall. The two drivers in front of him both drove for his team. Michael Waltrip took the checkered flag -- his first win in 463 Cup starts. Dale Jr. finished right behind him in second. NASCAR fans will argue until the Rapture about what Dale Sr. was doing on that last lap. Was he trying to win the race, or blocking the rest of the field from catching his friend and his son? The story ends the same either way. He spent his last moments at his son's back.

NASCAR races at Daytona twice a year. The July after his father died, Dale Jr. headed to Florida early. There used to be a week off before the Daytona summer race, and for years he and his buddies had enjoyed the beach before the crowds showed up. That year, when they got to town, they went to the speedway and found the gate open. Dale Jr. drove his Suburban onto the track. They were going about 35 when a security guard cut them off, furious. Then he saw who was driving. He let Dale Jr. finish the lap.

They got to Turn 4. The skid marks were still on the track.

Dale Jr. got out and took a walk around. He didn't know how he would feel. He just tried to soak in everything in his life, and his father's, that had put them in that place together. "If I had any issues, I was going to find out that moment," he says. "And I didn't."

He decided then that Daytona would always be sacred to him.

A week later, in the first race at Daytona since his dad's death, Dale Jr. won the Pepsi 400.

Sixteen years later, Daytona will be where his comeback starts.

He feels 100 percent healthy, though he knows each concussion makes it easier to get the next one. He plans to donate his brain to science. Maybe it will help make racing safer, but racing will never be safe. The danger is the attraction. Dale Jr. talks about how you can get an inch or two from the wall at some tracks and compress the air into a cushion that makes the car go faster. But get too close and you're into the wall. That's the thrill of it -- that tiny space between joy and disaster.

Off the track, for now, he has found the cushion. He and Amy got married on New Year's Eve. They Instagrammed their honeymoon in Hawaii, drinking cocktails and watching whales, looking happy and relaxed. Dale Jr. hopes he and Amy have children. Most of the people close to him already have kids. It is a different kind of race, and he is behind.

He also wants to run fast on the track. He wants to win more races -- he has 26 wins in his Cup career -- and maybe the Cup championship he has never won. He's on the last year of his contract with Hendrick. He plans to race for a couple of months, see how he feels, before he decides whether to sign up for more. After his time off, retirement no longer feels like a distant notion. "I've done everything I ever thought I would do," he says. "I've done more than I thought I was capable of doing. I look at my trophies and can't believe they're mine."

But his mind is still not quite settled. As much as his time off made him a better human being, it couldn't replace the feeling he gets inside a race car -- that happiness at making so many other people happy. "I've had a hard time trying to find something that's comparable," he says.

He wouldn't race if nobody was watching. That's the whole point. He wants his fans to watch him, he wants his team to care about him, in the same way all those years ago that he wanted his daddy to notice him. That's why he got in the car. That's why it's so hard to get out.

Racing has wrecked his family and battered his brain. But he has hauled it all back to the shop and rebuilt it one more time.