Casey O'Brien has always needed a team.

As a kid, when his dad, Dan O'Brien, worked in the Gophers football department, he was always around the team. As a 13-year-old freshman quarterback at Cretin-Derham Hall, he led the team. After his bone cancer diagnosis that year, he switched to the less-risky position of placeholder to remain with the team.

He sought out the Gophers and coach P.J. Fleck for a walk-on opportunity in part because they were the only Division I team that would medically clear him. As he's battled cancer relapses, he's inspired fellow childhood cancer patients, forming relationships with them and building his own team.

That's where O'Brien derives his improbable strength, through about 20 surgeries and five chemotherapy treatment plans, to become a five-time cancer survivor, his most recent battle just won in May.

"Just being around positive people," O'Brien said. "I feel like I'm lucky to have a really positive group of friends and family that have carried me through the whole experience."

O'Brien relies on that support. The St. Paul native's summer and fall were like a movie, filled with harrowing moments and unexpected triumphs. It started in July, when he shared his story in a speech at Big Ten Media Days, garnering national attention. He appeared on ESPN's "College GameDay" and won the Disney Spirit Award. He made his collegiate debut, holding the ball for several perfectly kicked extra points in conference play.

With that exposure, the 21-year-old became a source of hope for childhood cancer patients across the world, forging personal relationships with many while bringing awareness to his osteosarcoma disease and the M Health University of Minnesota Masonic Children's Hospital.

But his own battle wasn't finished.

While the 10-1 Gophers readied to face rival Wisconsin in the final regular-season game this past November, O'Brien went in for his routine three-month scan, which revealed a spot in one of his lungs. The ensuing four-hour surgery days later prevented him from playing.

Fierce determination

Dan O'Brien said that was one of the hardest days because it caught the whole family off-guard after a run of unbelievably good moments. But Casey O'Brien "broke out" of the hospital early, appearing on the field pregame just days after his operation. He wasn't going to miss sharing that moment with his team.

He worked through his recovery in enough time go to Tampa, Fla., for the New Year's Day Outback Bowl, even though he couldn't play.

The story took yet another twist when he returned home, and a checkup showed a spot on his other lung, requiring more chemotherapy and another surgery in March. While he couldn't participate in the Gophers' spring practices, O'Brien worked out with his teammates three to four times a week, amid six-hour treatments every Friday.

Then came the coronavirus pandemic, which has separated the entire Gophers team for the foreseeable future.

Football has long been O'Brien's respite. While he fought to survive cancer, he kept his eye on early June, trying to keep his weight up and his body in shape so he could compete for the starting holder job.

"That's kind of his release, a little bit. That's his alone time," Dan O'Brien said. "He puts his headset on, and he works out. He feels better when he works out. And when he works out, he feels like he's a college football player. He doesn't feel like he's a cancer patient that can't do anything but sit around and watch TV or play video games.

"That's kind of what helps him experience normal. I think that's all he's ever wanted."

College football's future, though, is still murky. The Gophers could potentially return for summer workouts this month, though what kind of season will follow is unknown. The chemotherapy slightly weakened O'Brien's immune system, and each surgery has taken a small bit of his lung, meaning any illness that affects the respiratory system is especially dangerous.

But O'Brien has never been one to worry, trusting in himself to know what he can handle. He doesn't question if his knee, surgically replaced after his initial cancer diagnosis, can hold up to all the starting reps, if his next scan in July will stay stable, if going to practice will put him at risk of contracting the virus. Not if it means staying away from his team.

Because of everything, that's actually been the hardest part of these past few months.

"We're from all over the place, and you get used to being around all those guys, and then you don't see them for two, three months. It's weird," O'Brien said. "We Zoom, and we do all that kind of stuff, but it's not the same as hanging out in the locker room."

Planning big

It's been the same for O'Brien's other team. He's used to popping his head into hospital rooms to meet other patients. He still stays in touch through social media and video chats, even recently talking with a family from Illinois that just reached out about the daughter's osteosarcoma diagnosis. Those fill the void for now, but O'Brien craves real time with his people.

"It's hard to understand and hard for me to explain," Dan O'Brien said, "how important Gophers football has been to him and his recovery, on the bad days and good days."

On those good days, O'Brien is full of plans. For what his Gophers team can accomplish this fall, for graduating a semester early with his finance degree, for internships, jobs, having a family of his own, moving somewhere warmer.

The darker moments — he doesn't share with many. That late-November day when his fifth round with cancer began was one of the bad ones.

"I remember just being so down," O'Brien recalled. "And I wasn't as much down about the fact that, like, the cancer had come back. Obviously, that was a big part of it.

"But I think that I was more sad about the fact that I wasn't going to be able to dress [in uniform], and I wasn't going to be able to be on the sideline for a game that was to go to the Big Ten championship, and it was 'College GameDay,' and there was so much energy around that game.

"And I felt like I wasn't going to be a part of it anymore."

But that could never be true. Because this past season, it wasn't really Gophers football without Casey O'Brien.