You don't know Derek Wolfe, and he doesn't care.

You catch glimpses of his life through Instagram, but what's beneath the surface can stay there for all he cares. If people only think of him as a vicious defensive end, that's fine with him.

For the longest time, Wolfe's personal life was something he wanted to keep hidden. Abuse, life in an unstable home before eventual homelessness, depression — these are things he naturally doesn't want to dwell upon.

It wasn't until this year, after finding stability with two long-term commitments — one with the Broncos after signing a contract extension in January and one with his wife-to-be in May — that he could turn toward the future.

With that peace of mind and support, Wolfe is now able to turn his focus completely to football, determined to show that his 2015 season is still just the beginning of a maturing career.

Security and loyalty are two inherently important values to Wolfe. That combination led him to sign a four-year contract extension just before the beginning of the playoffs rather than during the free-agency period, when more teams would have been able to make offers.

But Wolfe didn't want any more uncertainty. He's had far too much of that in his career and his life already.

Almost three years before you saw Wolfe terrorize Ben Roethlisberger, Tom Brady and Cam Newton en route to a Super Bowl 50 victory, Wolfe had been bound to a stretcher and loaded onto an ambulance on the field during a 2013 preseason game.

A cut block knocked Wolfe to the ground. Then, while scrambling to his feet, Wolfe received a devastating helmet-to-helmet blow from Seahawks fullback Michael Robinson. Wolfe was rendered temporarily immobile and unable to feel his extremities. After being taken to the hospital, Wolfe was diagnosed with a spinal contusion — a bruise on his spinal cord.

In the three months that followed, he discovered that he was not the same person he was before. Amid a strenuous workout routine, Wolfe could not keep his weight and dropped 30 pounds. His mental health also suffered because of stress, and Wolfe slipped into depression.

It all came to a head in late November on a team bus ride before the Broncos' road trip to Kansas City. Sweating profusely while his vision became blurry, Wolfe began having a seizure. Teammates and trainers rushed to his side as they yelled for the bus to stop. An ambulance arrived to take Wolfe to the hospital, but he kept breaking free from the restraints, which forced paramedics to induce a coma, Wolfe recalled.

Wolfe awoke a day later, and two or three days after that, he was released from the hospital.

Wolfe's depression deepened as he became a shell of himself. He held on to hope that he could return for the playoffs, but just one day at practice convinced him that he wasn't ready. The Broncos placed Wolfe on injured reserve a little over two weeks later, just before the team beat the Patriots to advance to Super Bowl XLVIII.

What he found in recovery was the loyalty and bonds that he knew were irreplaceable. He wanted to stay with the organization that stood beside him in the hospital room, the team that stood behind him while he worked his way back into football shape.

"Going through an injury where I'm having seizures and other things like that — John Elway, he had my back the whole way through it. All he cared about was my health and seeing me get back on the field," Wolfe says. "He just wanted to see me be healthy again."

Wolfe hadn't had that kind of support and trust around him often, especially when he was growing up. His stepfather physically and verbally abused him, but when his stepfather divorced Wolfe's mother, he stayed with him because of his mother's alcohol problems. But after his stepfather got remarried, his new stepmother threw him out of the house. To keep up the appearance that he wasn't homeless, Wolfe stayed briefly with a friend, then his grandmother, then both of his aunts. He wasn't on the streets, but he didn't find a more permanent home until that friend's mother picked up on what was happening and offered him a place to stay for good.

"I felt like I had to make a decision," Wolfe says. "Do I stay here with these people who actually care about me, or do I take my chances and go somewhere else, get an even bigger payday and this and that? And I was like, 'You know what, I'd rather just stay somewhere where I'm comfortable.' … It made more sense to stay here and be where I like to be and be around the people I love to be around."

Wolfe's slow, measured recovery paid off in a huge way in 2015. Though he missed the first four weeks of the season due to a league suspension, when Wolfe returned to the Broncos' league-leading defense, he came back a different player.

"You all are going to see a new Derek Wolfe," Von Miller told media in October. "I had already begun to see it [before the suspension]. I know from my experience what it takes to change yourself and reinvent yourself. I started seeing Derek do the same type of stuff."

Wolfe was already a destructive player in the run game, but he added the pass rush moves that made him one of the league's best three-technique defensive ends. He finished the regular season and playoffs with 11 tackles for loss, as well as eight sacks, 18 quarterback hits and 64 total tackles. Wolfe garnered AFC Defensive Player of the Week honors in Week 8 against the Packers, making seven total tackles, including one for a loss, and the Broncos held Green Bay to 140 net yards.

"He's a lot better pass-rusher than he was starting out last year and he's learned a lot and he's gotten better and better," Defensive Coordinator Wade Phillips says. "The last part of the year, he was really our best inside pass rusher."

From there, Wolfe is focused less on adding to his skill set and more on fine-tuning them to be more dominant.

"I have the foundation built," Wolfe says. "So I just keep honing in, just keep mastering those skills and keep finding other ways to get to the quarterback and other ways to use my hands better. Every day I just work on something different. I just practice things I'm not good at and end up being good at it."

That focus is what makes Wolfe a great player instead of merely a good one. Now with his career and personal life in a sound place, Wolfe is in a spot where he can hone his focus without worrying about much else, which should be the Broncos' windfall.

"Everything that I've been working for my whole life is starting to come together," Wolfe says. "Now I can focus more on my family and football. Those things are what are important to me. I never really had a true family so I'm trying to build my own now."

This is just the beginning for Wolfe, who is building more than just a career he's long desired.

"When I'm an old man and I'm sitting there and seeing my wife, my kids and my grandkids and all that stuff, that's when I feel like I've accomplished something," Wolfe says. "I just want to be able to give the kids that I bring into this world a chance like the chances I didn't have."

It's very easy to see Wolfe, like many athletes, as a superhuman character. He has incredible athletic gifts and he even howls after big plays. But at the center of it all, his story is a very human one.

"That's the beauty of life," Miller says. "Overcoming stuff, being triumphant, grinding and trying to make it to the next level — Derek is a prime example of that."

So now, in a way, you know Derek Wolfe. He still won't care, but if you see him howling even more this year, you might know why.