Vontae Davis sat in a red chair along the wall of the library at Dunbar High in Washington, hands in his lap and eyes straight ahead. He listened to Tiresias McCall, Dunbar's dean of students, introduce him to schoolkids sitting in rows of plastic chairs.

"This man used to be you," McCall said on a recent Friday afternoon. "He did what it took to make it up out of here."

McCall listed Davis' accomplishments since he graduated from Dunbar in 2006. They included all-America teams at Illinois, becoming a first-round draft pick and earning Pro Bowl appearances and millions of dollars during a 10-year run as an NFL cornerback — a career Davis ended in extraordinary fashion.

"We always say if you work hard, you pave your path," McCall said. "[If] you do what you're supposed to do and make the right decisions, you can leave on your own. His justification for doing what he did was, 'Leaving was therapeutic.' Out of everything he accomplished, out of all the money that was on the table, millions of dollars on the table, he decided, 'I don't want to do this no more.' He left on his own."

Davis tapped his fingers on his knees and nodded his head.

"With that being stated, let's give Mr. Vontae Otis Davis a standing applause."

Davis had not been back to Dunbar in years, since before the District of Columbia replaced the old building with a $100 million edifice that includes a plaque on the floor with Davis' name on it. He had returned hoping to provide inspiration with his story, which he recently memorialized in print. He brought with him a cardboard box filled with copies of the book he wrote with author Sean Jensen for the "Middle School Rules" series, in which professional athletes share lessons from their childhood.

It is a book for children, but Davis and Jensen only lightly sterilize the turbulent details of Davis' early life. Davis describes his father barging into their home bleeding, with sirens blaring outside, while Davis protected younger siblings. He shares how he cared for his baby sister and brother on mornings his mother had gone missing. He tells about his grandmother saving him and his six siblings — including older brother Vernon, now a tight end with the Washington Redskins — from foster care by adopting them after his mother spiraled into crack addiction.

"He made himself vulnerable," Jensen said, "to tell his truth."

Davis started writing the book about two years ago. He never envisioned his football career would be over by the time it came out. He certainly didn't think he would become known for one of the most memorable departures ever witnessed in professional sports.

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For all he achieved in football, the general public remembers Davis for how he left the sport. In Week 2 last season, Davis made his debut for the Buffalo Bills. An uneasy feeling overcame him on the sideline, and he told coaches and teammates he was finished. He retired at halftime, leaving the stadium as the game played on.

He feels no compulsion to explain his exit but has no reticence in doing so. Davis wants to serve as an example to kids, and while even he does not understand precisely where the impulse to stop playing came from, he believes the way he finished his career connects to how he grew up.

"I think it's more powerful how I ended," Davis said. "We all got stories to tell."

Davis started last season intent on proving himself, his dedication to football as strong as ever. His six seasons with the Indianapolis Colts had ended on a sour note, with a benching and a groin injury. In February, Davis signed a one-year, $5 million contact with the Bills, viewing it as a chance to show he had more good football in him.

By summer, though, his wife, Megan, was certain it would be Davis' final season. She had watched his body deteriorate, unable to recover with the same speed it once did. "You don't have to play anymore," she told him at one point during training camp. "You've done enough for our family." But she knew her husband was determined, a byproduct of his childhood.

"The whole time he was in Buffalo, his body and his mind I don't think were on the same wavelength," Megan said. "One was a lot older than the other."

Still, Davis worked with his future in mind. He sat out Buffalo's opener as a healthy scratch. During the next week, assured he would play, he studied and practiced like always. He woke up Sunday feeling confident and prepared, telling himself what had become his game-day mantra: "I'm going to have the best game of my life."

When he returned to the sideline after a series in the first half, something felt out of place. He describes the sensation now as an "out-of-body experience" and a "spiritual moment." He had never felt anything like it on a football field. He heard a voice: "I have given all I've got. Leave this chapter behind."

When Davis reached the locker room at halftime, he removed his No. 22 Bills uniform and texted Megan, "I'm done."

The exact timing surprised Megan. The decision did not. "I guess I'll meet you at home," she told him. Davis drove himself. He left behind any personal belongings and never returned to the Bills' facility to gather them. Back at their house, he and Megan poured two shots of Don Julio 1942 tequila and toasted.

They had friends in town, and as they talked over Davis' decision, the public discourse became unavoidable. "We kind of engaged in the social media trolling," Megan said, laughing. They saw him called a quitter, or laughed at, or used as a way of poking fun at the Bills, who lost in a blowout.

One teammate, Lorenzo Alexander, said Davis was "completely disrespectful" to teammates by "quitting" on them. Others called him Sunday wondering what had happened. On Monday, LeSean McCoy and Tre'Davious White, two of Davis' closest friends on the Bills, visited him on their day off to offer support.

"Everybody thought I was crazy," Davis said. "But I was perfectly fine."

Davis released a lengthy statement, writing, in part: "Today on the field, reality hit me fast and hard: I shouldn't be out there anymore. It's more important for me and my family to walk away healthy than to willfully embrace the warrior mentality and limp away too late."

When he fell asleep Sunday night, Davis felt a liberation so unfamiliar it was awkward. Since he could remember, Davis had lived on someone's else schedule. When he woke up, there would be no meetings, no practice, no workouts, no film, no coach's orders.

"It felt good to have choices and decisions that you want to make," Davis said.

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On the morning of his high school visit, Davis arrived at Achievement Prep's middle school with Jensen and Kenneth Ward, a former teacher and mentor to Davis who now serves as the executive director of D.C. nonprofit College Bound. Kids in red-and-white uniforms gathered in a meeting hall, seated around circular tables.

"My mother, she was a great person," Davis said. "She had a great personality. When she did drugs, she was a different person."

He told a story about his friend Ronnie, a troublemaker whom he learned to avoid — one of the book's rules is to choose friends wisely — and who is now in jail for killing someone. Jensen asked who knew what jail was. Every hand in the room went up.

Davis later noted with sadness how much the kids knew about prison and foster care. In Florida, where he lives in retirement, he has shared his life story with juvenile delinquents. In Indianapolis, Davis worked with kids in foster care.

"Since I've met him, he's always had a profound inclination to want to help people who were in similar circumstances as him," Megan said.

The trio then drove to Dunbar, where Davis grew emotional as he described the long odds of reaching the NFL and the importance of education.

"I'm only 31 years old," he told the students. "I got the rest of my life in front of me. You can't use your physical ability for the rest of your life. But you know one thing you can use is this right here — your mind."

He mentioned his book.

"My mother was addicted to drugs, crack," Davis told them. "Do you know what crack is? You know what crack does to you?"

A chorus of "yeahs" came back.

"There was times I would wake up in the morning, and I wouldn't know where she was," Davis continued. "I'm 11 years old. Eleven. I got to take care of my siblings, my sister. Baby's crying. I don't know what to do. But one thing I learned from the situation is, your circumstances don't make you. You make your circumstance. So for the ones who are going through stuff in life and come in here, still have to play, still have to focus, I did those things. So I know what you're going through."

"I come from the same environment," Davis told the room, his voice cracking. "But this message means more to me. It means more to me, because I'm not just a football player. I want to leave you guys with knowledge. ... That's why I came back, because I care about you guys, man. Y'all my brothers."

The kids applauded, and Davis took questions. Who's the best player you ever guarded? How did you transition to college? Did you play other positions? Then one student stood in the middle of the room and asked something more complex.

"Do you look at the NFL as modern-day slavery?"

The student sat down. The room hushed. McCall's eyes bulged. One teacher chuckled and asked if he should turn off the camera he was recording with.

"I look at it like this, man," Davis told the room. "My story, how I walked away from the game, the game did not use me up. My talent and my ability, I was blessed with that. I thank God for that ability. I was able to play in the NFL. The NFL blessed me to do other things in life. But like I said, it's a business. ... It's a business that uses 70 percent African Americans. Use 'em up, devalue them and get rid of them. And it's modern day. That's all I'll say."

McCall turned to Davis and continued the conversation.

"To add to that, sir — I accept your response — but normally when we speak of slavery, it's hard labor with nothing in return," McCall said. "Does that still apply to you now? ... You walked away on your terms and started your own business. When we talk about the context of slavery ... "

"I got you," Davis said.

"... Is it slavery still?" McCall asked.

"No," Davis said. "It's not modern-day slavery. I was able to take advantage of my opportunity."

"But are you also an anomaly?" asked Ward, Davis' old teacher, from the edge of the audience.

"Absolutely," Davis said. "Yeah."

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To write "Middle School Rules," Davis relived the traumas of his past. He had long before made peace with his childhood, but he had moved forward, always toward the next game or the next goal, without confronting the emotions it left him carrying.

"It was very hard at first," he said. "As I told my story more and more, it brought up emotions that, it was hard to really process at the time."

He discussed stories with family members that had stayed taboo. Remembering some moments made him happy, such as the time his grandfather saved him from choking on a Jolly Rancher. He also recounted the time his mother showed up at elementary school recess high on drugs, yelling at him from outside the fence, leading to days of teasing. He told Jensen during their process that his relationship with his mother is as good as it has ever been.

"I think he was able to gain some closure from his childhood," Megan said.

Davis believes his book can show kids from backgrounds like his that they can transcend their circumstances. Starting in his third season, Davis studied finance and budgeted as if he had already retired, saving money as if every paycheck was his last. Three years ago, he began to study business, and he now owns and operates a wellness spa, VZONE, that specializes in oxygen treatments.

But even though he prepared himself for it, Davis had never considered retirement before the moment it came. More than a year later, Davis understands with no more clarity where the sudden urge — that out-of-body experience — came from.

"My spirit talked to me that day and told me to leave the game," Davis said. "Looking back, it's one of the best decisions of my life."

He does not regret anything. He feels happy and healthy, his body and mind preserved and fresh. He probably would feel no different today had he simply played the second half, but he never even considers finishing the game as a second thought. He believes now what he believed then: What he felt on the sideline in Buffalo presented him an imperative, not a choice.

"At the moment, I didn't think about any of that," Davis said. "My intuition led me to it. It was bigger than me. A lot bigger than me, for sure."

In the days after Davis retired, Megan asked him if he was OK so often that he asked her to please stop. When she stopped worrying about her husband, Megan realized she had never seen him happier.

"A lot of people don't realize the stress — not just the physical, but the mental stress it takes to play in the NFL," Megan said. "Having that load lifted was kind of relieving. And he gave everything he had to the game."

The public thinks it knows Davis for one moment. Really, his entire life shaped it, led to it. He sees a connection between how he grew up and how he ended his career. Davis overcame circumstances unfathomable to most, and it earned him profound control of his life. He used football for as long as he chose, and not a second longer. He paved his own path. Now, he has written the first part down. The rest of his story is only beginning.