This was the Alex Smith comeback years in the making.

He had endured a gruesome compound fracture in his right leg that led to a life-threatening infection but persisted through all of it to make a triumphant return to the N.F.L. Months later, in the spring of 2021, he stood with his family on a slope in Big Sky, Mont., ready for the next part of his life.

Rehabilitating his injury for his football comeback, Smith said, “was always just a means to get the rest of my life back.” As a kid, he’d enjoyed the slopes with his parents and siblings. He had not skied since he entered the N.F.L. because his contract barred him from doing so, and he hoped his future could include creating wintry memories with his three children.

So Smith stood on top of a mountain on a leg rebuilt through 17 surgeries (“or 18,” he said. “I forget at the end,”) and hoped that if he could make it down, he’d get to be the kind of present, active parent that Doug and Pam Smith had been to him.

He exhaled and safely whooshed downhill. Shortly after, Smith decided to retire from the N.F.L. even though teams still wanted him. His body had recovered and Smith now had time for the life that football had stolen from him. He planned on crushing his sons, Hudson and Hayes, now 12 and 10, in basketball, taking them and his daughter, Sloane, now 7, to school most mornings, and accompanying them on every skiing and snowboarding trip.

Taken No. 1 overall in the 2005 N.F.L. draft (23 picks ahead of Aaron Rodgers), Smith had become a steady starting quarterback for San Francisco, Kansas City and finally Washington, driven initially, he concedes, by a fear of failure. He managed by learning to control what he could.

The long slog of rehabbing his leg was one of those controllable aspects of his career, and his return from the horrific injury became the defining triumph of Smith’s 16-year professional career. The hill conquered, Smith slipped into an idyllic vision of retirement. The family started building their dream home. He coached Hudson’s flag football team and began doing some football commentary for ESPN.

It lasted almost a year, until the day in May 2022 that upended everything.

Sloane had been sluggish earlier, but that night Smith’s wife, Elizabeth, noticed their daughter was not using her right arm and was slurring her words. She screamed for him to call 911.

Doctors discovered a brain tumor and rushed Sloane in for an emergency craniotomy to remove it. As they rushed her into surgery, Alex Smith felt a new terror.

He’d never been scared, he said, when doctors mentioned his right leg might have to be amputated. Or when he lined up under center and put that leg in the sights of 300-pound men sent to crush him. Smith still felt like he had some level of control. It was his body on the line.

“It’s different when it’s your little girl and you’re helpless with how terrifying that is.”

Sloane is too young to recall much of her father’s playing career.

She was 2 years old when Smith had Washington atop the N.F.C. East, hosting the Houston Texans just before Thanksgiving in 2018. He’d lived a couple N.F.L. lives by then — labeled a draft bust in San Francisco before Coach Jim Harbaugh turned his career around; steadied into a playoff contender and regular Pro Bowl selection in Kansas City before Patrick Mahomes took over.

Quarterbacking Washington that day, he dropped back on a third-and-9 and two Texans converged, landing on top of him. Smith knew his leg was broken before a fuzzy haze completely enveloped him. He didn’t see pieces of bone jutting through his skin. Elizabeth rose from her seat. She saw Smith grab his leg, but couldn’t tell if he had hurt his ankle or foot. Hudson grabbed her close as workers rushed to wheel a medical gurney onto the field in Maryland.

Smith endured four separate hospital stays in nine months to save his leg. Hospitals always have an antiseptic odor in the air, one that came to represent for Smith a mixture of hope and angst.

The familiar scent dredged up those emotions as Smith sat in the hospital during the 10-hour surgery to relieve the pressure on Sloane’s brain. Doctors described her having a slow-growing brain tumor they pointed out for him on her scans.

“You just have no idea what it means,” Smith said. “The words brain tumor are terrifying.”

The Smiths greeted Sloane after she woke from sedation after the procedure. She wiggled her right arm and spoke groggily, but clearly.

The family video called Sloane’s brothers. Sloane recalled that it was Hudson’s 11th birthday. Unprompted, Sloane slowly and melodically sang him “Happy Birthday.”

Alex Smith called Sloane into the family’s kitchen recently on a day before a new school year dawned.

“Come here,” he said, pulling her in for a hug.

“Are you wearing your mom’s perfume?” Smith asked, whiffing the air.

“No,” Sloane said, smiling sweetly and unconvincingly. “It’s lotion.”

It’s part of a daily fight the Smiths have largely forfeited. Sloane will find herself in her mom’s makeup or perfume. On one hand, Elizabeth tells Sloane she’s too young to leave the house wearing that stuff. Elizabeth also reminds herself that she wants her children to live their lives.

“We try not to parent them differently,” she said. “But, I do have a different perspective on kids and their childhood now.”

Doctors were not able to remove Sloane’s entire tumor, which was later found to be malignant, in the first surgery, so she needed a second 10-hour procedure this spring. “We found out last fall that essentially that they had missed a piece, that there was a little piece in there left over,” Alex Smith said.

The family lives “scan to scan,” with Sloane’s prognosis. She’s suffered two seizures, Smith said, and the family recently had a meeting with her school about her emergency rescue drug.

The mind leaps ahead, Smith knows. When his does, he tries returning to the moment. What are the facts? What do we know? What’s the reality?

“I spent so many times going down these rabbit holes of what I’ll ever be able to do again and my prognosis,” he said. “And what does that do for you? It’s not doing any good and certainly it’s far harder as a parent, but no different.”

He added: “I don’t know if you get any better at it. This is something that’s so much bigger and harder. Do you get better at compartmentalizing? I don’t know. I don’t know. I’m not sure.”

Elizabeth projected strength during Alex’s recovery and return, telling herself that she could not be the weak link. “This is something that I don’t know where the end is,” she said. “We don’t know because of the rarity of her tumor, when it will pop his head back, if it will pop its head back.”

So the Smiths try to maintain a sense of normalcy and count daily victories, especially those on the way to Sloane’s goal of dancing competitively.

“She’s a little badass,” Elizabeth said, adding: “They know that you can overcome things, and you can fight through, and you can go back to living your life. Right? They got to go through that journey with their dad. I think it’s probably hopeful for them, right?”

Before her surgeries, Sloane was their most independent child, the one who could be swaddled and then sleep on her own through the night. The Smiths moved her into their bed following the first craniotomy so she could be properly propped up. They relished every late-night smooch and cuddle.

Sloane recently requested to sleep in her own bed the night before the new school year.

Elizabeth Smith noticed the devastation creep onto her husband’s face. She told him it was good that she was working her way back toward her own room again.

The next night, though, Sloane sleepily returned to her parents’ room.

Alex Smith lit up. Fear strangled him early in his N.F.L. career. He tries to now snap himself into the present and control what he can.

He has this time to be the type of father he hoped to be.

“She’s back,” he said.