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The Mack linebacker, playing Cover 3, sets his sights on the wide receiver catching the ball over the middle. He closes in and hits the wide receiver's torso with his helmet. The wide receiver bounces off the tackle attempt. The Buck linebacker is there to finish him off.

The Mack linebacker stays on the ground. Trainers rush out. As the medical staff tends to him, it becomes apparent he cannot move his legs. Paul Brown Stadium is hushed. The Buck linebacker takes a knee. They strap the Mack linebacker to a spinal board and carry him to a cart. As the cart drives into the tunnel, the Mack linebacker puts his hands over his eyes.

On the next play, the call comes to the Buck linebacker from the sideline, but he is too dazed to take it in and relay it to the rest of the defenders. He is overcome because there is an affection between him and the Mack linebacker—one that usually has no place on a football field.

This is the story of a friendship. It's an unlikely friendship that has transcended football, has transcended tragic circumstance.

Evidence of it trickles down Vince Williams' left cheek as his friend Ryan Shazier's life changes forever.

On the evening of May 8, 2014, most football fans are watching the NFL draft. Williams is sleeping. When he wakes, he has more than 20 texts and a couple of voice messages, including one from his agent. It turns out the Steelers used the 15th pick of the first round to take Shazier, an inside linebacker out of Ohio State. A player who could take Williams' job.

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Williams is angry. He is miserable. At an OTA the next day, his coaches try to tell him everything will be OK. The words sound hollow, and he does not want to hear them.

Williams is a sixth-round pick, and in his mind he will always be a sixth-round pick. Now this hotshot, in his mind, is a threat to take his roster spot.

Shazier is an instant starter. Williams makes the team as a backup and specials teams player.

The following spring, Steelers linebacker James Harrison invites some of the defensive players to work out in Arizona. Williams says he's in. Then he finds out Shazier is in, too.

To keep costs down, a group of players decide to rent a house. Jarvis Jones, Sean Spence, Williams and Shazier become roommates. Jones and Spence fly back home on weekends, so that often leaves Williams and Shazier alone—uncomfortably alone.

Williams needs to outwork his competition. His mindset is it's the only way he can win. He wasn't even invited to the combine, and then he ran a 4.72 40-yard dash at his pro day. Some scouts timed Shazier at 4.36 at his pro day.

Williams is not like Shazier, and he knows it. But damn if Shazier isn't working as hard as he is.

Neither will let up. And neither wants to allow the other to have an edge. They train twice a day, six days a week, sprinting, jumping, squatting, pushing, pulling, lunging, rowing. When the trainer tells Williams to do 10 reps, he does 13. And then Shazier does the same. When the workout is supposed to be over, Williams stays for extra sprints. With Shazier by his side.

First-round picks like Shazier, Williams always thought, were cake eaters. But he's never seen a player with Shazier's pedigree work like he does. He has to respect that. And he even has to change the way he thinks.

So they start encouraging one another. And they start hanging around.

Williams doesn't want to like Shazier. But he can't help himself. They talk about their goals, their relationships, what they want for their kids, what they want from football.

"I don't need to be in the NFL top 100," Williams tells Shazier. "I just want people to walk up to my children and say, 'Your dad was a monster.' That will be all the affirmation I ever need."

Shazier is different. "I want to be a gold jacket guy, the next Derrick Brooks," Williams remembers him telling him. "I'm going to be like Von Miller, a guy who gets the commercials."

By the time they report to OTAs, they have a bond.

Going into the 2017 season, Shazier and Williams believe they are on the verge of accomplishing special things together. They decide they need a nickname. Shazier is the idea guy.

"How about Splash and Dash?" he asks Williams. "Crash and Bash? Thunder and Lightning?"

No, no and no.

This goes on for a while. Then one day Shazier calls. "I'm watching Talladega Nights, bro," he says. "I got it. Shake and Bake. Say it, bro. It sounds great."

Williams: "That's stupid."

Shazier: "No it's not. Everybody will know what it means, and it's going to be great."

Williams goes along, and Shake and Bake becomes a thing.

Bake—or Williams—compares himself to a cactus. But people who know him best say he's more like a rosebush. He will tell you he is prickly and not trusting or friendly. He suspects everyone wants something from him. He is offended easily.

Shake—or Shazier—exudes warmth and is a magnet. He is the friendliest person Williams has ever met. He would rather go with the flow than say no. He is impossible not to like.

"You are too nice," Williams tells him.

Where Williams sees darkness, Shazier sees light. Williams doesn't want you on the bandwagon. Shazier makes room for all.

They go to a Penguins game. Williams wants to go unrecognized, but Shazier draws a crowd and revels in it. With a 100-watt smile, he signs every program, scrapbook and napkin that is presented. When Williams is approached, he responds: "You don't want my autograph. You don't even know who I am."

Shazier likes to go out. Williams likes to stay in.

The concept of being a celebrity does not sit well with Williams. It sits very well with Shazier. At a Cavs-Celtics game in Cleveland, Celtics coach Brad Stevens sees Shazier and invites him and his guest on the court. They meet the Celts and Cavs. Williams shakes his head. "Only you could pull this off," he mutters.

Williams is way over here; Shazier is way over there. This is how it works.

Williams buys a nice house in the Pittsburgh area. He pays about $700,000 for it and is proud of it. He gives a tour to Shazier, who tells him he also is house hunting. Shortly after, Shazier shows Williams his new house—a $2.6 million estate.

"Ryan, you have you, your girl and one kid," Williams tells him. "Why do you need all this?"

Williams is understated; Shazier is overstated.

They are opposites on the field too. Williams is a blunt instrument of a linebacker; Shazier is a sharp object. Shazier approaches game day with a calm, detached demeanor. Williams plays red-hot, looking for slights whether or not they exist.

Did that guy just look at me funny? Their inside linebacker thinks he's better than me. They are trying to make me look bad.

Williams is pragmatic. Shazier is a dreamer. During training camp, Shazier has another idea.

"We not believing no more," he says to Williams. "We Shalieving."

Williams cracks up. "That sounds horrible." he says. "That's stupid. Get out of here, man. What a clown."

Shazier: "You'll see; there will be a banner in the stadium that says 'Shalieve.'"

And at the Steelers first home game, the banner is there.

And now, Williams wears a black T-shirt with "Shalieve" written in gold on the front.

What Shazier wears often is fodder for Williams' barbs. His tight jeans, short shorts and loud blazers elicit ridicule.

Shazier gives it back, though. He tells Williams when he dresses up he looks like a deacon at a church service.

They are reflections of their roots.

The street lights from the Central Florida town where Williams grew up are from another era. It wasn't long ago that Davenport opened its first Super Walmart. Not too many people make it out of Davenport with success stories. Most dreams, he learned, are laughed at.

Shazier grew up in Florida too, but it was another world. He lived in a mixed area of Fort Lauderdale, not far from fabulous beaches, luxury hotels and swanky restaurants. His father, Vernon Shazier, has been a pastor and team chaplain for the Miami Dolphins, so Shazier saw achievement all around him.

Somehow, they relate to one another like few teammates can.

In the fall of 2017, pro scouting coordinator Brandon Hunt gives a report on the Steelers' upcoming opponent to the defense. Seated side by side in the meeting room are Shazier and Williams. Later in the day, in the locker room, they hang together. And on the practice field, they never seem to be far apart. The next morning, at 6, in a dark, quiet meeting room, they study tape.

Away from the team, it's the same. Williams is at Shazier's house a lot. They relax by the firepit in the backyard and talk smack with other teammates and Shazier's homie/trainer, Jerome Howard. They watch sporting events and play Madden and NBA 2K. Williams' five-year-old twin sons and Shazier's five-year-old son splash in the pool.

They go to movies with one another. In fact, they try to see every movie worth seeing. When Shazier sees a movie without him, Williams gets pissed. Together, they have been looking for a new church.

Shazier has food allergies that restrict his diet, but he can eat steak. So he and Williams go to steakhouses. Shazier orders the tomahawk ribeye, Williams the porterhouse cut off the bone.

When they are separated, they text snippets of game tape to one another for advice and critiques.

Their fiancees know each other well. Their mothers have each other's phone numbers.

Shazier introduces Williams to a friend from back home. "This," he says, "is my brother Vince."

The game plan for an October matchup against the Jaguars calls for Shazier to blitz. But it isn't working very well. He has an idea.

"I'm not getting home, so you go," he tells Williams.

They don't tell their coaches about the change, but their coaches can't be mad when Williams sacks the quarterback. Afterward, he and Shazier celebrate with their special handshake from Mad Max.

This is how they work together.

In the same game, Shazier recognizes the Jaguars are trying to isolate Williams on a screen pass, so he tells him to switch with him. Sure enough, they run the screen, and Shazier uses his speed to blow up the running back in the backfield before he can secure the catch.

They seem to always know where the other will be on the field. They execute each play with abandon as a result, because either knows if he misses, his brother will be there to clean things up.

Shazier is extremely confident. Williams recalls that Shazier made a prediction about him before last season, when he was replacing Lawrence Timmons in the starting lineup.

"You about to get double-digit sacks," he said. "You are going to be great. If Law Dog [Timmons] could do it, you can too."

Williams: "But Law Dog is a great linebacker."

Shazier: "You're great too. I'm going to get all the picks, and you are going to get all the sacks. Why are you worried about it?"

Williams: "You are a nut."

Shazier believes in Williams more than Williams believes in Williams. And as a result, Williams starts to believe in Williams more.

The clock hits zeros in the Steelers' 23-20 victory over the Bengals. Players from both teams converge on the field for hellos, goodbyes and well-wishes. But one player—Williams, the Buck linebacker—runs straight off the field. He is the first player up the tunnel and into the locker room.

"How is he?" Williams asks trainer John Norwig.

Shazier, the Mack linebacker, isn't here. He was taken by ambulance to the University of Cincinnati Medical Center.

Three days later, Shazier is transferred to the University of Pittsburgh Medical Facility. Williams can go see him now. But he doesn't like what he sees. Tubes are coming out of him like legs from an octopus. He still can't move his lower body. It makes Williams uncomfortable. But he deals with it because he knows his friend loves to have people around him.

Shazier, Williams thinks, doesn't deserve this. He has seen so many NFL players who take their blessings for granted, who don't care enough, who take shortcuts and have other agendas. Shazier isn't like that.

It is Shazier who lifts Williams.

"This ain't nothing," Shazier tells him while lying in his hospital bed. "Minor setback. I'm coming back from this s--t. Nothing going to hold me down. I'm going to be faster. I'll run a 4.2 now."

While taking on a more prominent role in the Steelers defense with Shazier out, Williams keeps tabs on his friend in the hospital over the next month. In early January, he is home talking to a childhood friend about Shazier. What he is telling his friend, he thinks, he should tell the world. And so he takes to Twitter, telling the story of their friendship.

Feeling starts to return for Shazier. He can wiggle his toes. He starts rehabbing. Williams is taken aback by the intensity with which he approaches it. He is there when a doctor tells Shazier he can't be sure where Shazier is in terms of progress because he has never seen anyone with a similar injury as far along as Shazier is.

Williams encourages him. "Be great," he tells him. "Be yourself. Attack it the same way you attack everything. Just be that guy. Ryan Shazier is better than this. You can't surprise me."

And then on a mid-January visit to the hospital, Shazier surprises him.

"I'm going in for rehab soon," he says. "Do you want to see me walk?"

"Are you kidding me?" Williams says.

Williams wants to see him walk. The therapist attaches leg braces and helps him keep his balance. And Shazier walks.

He walks.

By April, Williams notices Shazier is trying to walk more and more.

"I know what you're doing," Williams tells him. "The draft is coming up and you are going to walk across the stage to announce our pick."

Shazier: "How did you know that? Did somebody tell you?"

Williams: "Nope. I just know."

Sometimes, people who are so close just know.

With more free time, Shazier studies the game and comes to understand it better than ever. During offseason workouts, he drives a golf cart, offering pointers to teammates and creating a feel-good environment with his presence.

In one practice, Williams breaks up a pass. Hunt, who is sitting with Shazier, remarks it was a great play by Williams.

"No it wasn't," Shazier says. "He should have picked it."

Hunt tells Williams of his friend's critique.

Williams responds: "Yeah, that's because Ryan saw it through Ryan's eyes. He doesn't realize everybody isn't like him."

And that is Shazier's point. He wants Williams to be more like him. If Shazier can't be on the field, his eyes can be—as long as Williams can see the game the way he does.

If Shazier can't make these plays, he wants his friend to make them.

Shazier doesn't get emotional. He isn't bitter. But he misses the game.

Williams appreciates the game more than ever. He enjoys offseason workouts twice as much, for both himself and Shazier.

They have been able to participate in one sport together—bowling. In June, Shazier takes a cane in one hand and a bowling ball in the other and rolls a strike. But Williams has no mercy.

"I'm not going to let your handicap ass beat me," he tells him. "Save those sad stories."

Williams beats Shazier, and they laugh and they hope.

Williams once saw Shazier beat all of the Steelers wide receivers in a race. He saw him do reps with as many plates on the bar as Williams, even though Williams was 20 pounds heavier. He saw him refuse to use a walker to get to the bathroom when there was supposed to be no other way.

Williams will never doubt his friend, no matter what he's faced with.

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Williams believes things happen for a reason. This happened for a reason too. He thinks—no, he knows—that Shazier will serve as an inspiration for others and as a testimony to his faith.

Shazier and Williams want to be there at each other's weddings. They think about watching each other's children grow up. They plan on looking at each other's wrinkled faces and telling stories about the old days.

But for now, they dream of something else: lining up side by side in black and gold again, making a running back regret the moment he hit the hole.

Dan Pompei covers the NFL for Bleacher Report. Follow him on Twitter: @danpompei.