Duets: Chris and Aaron

Chris Henningsen was hoping that Aaron Kaercher would join his extended family for Christmas brunch this year , and Aaron knows why.

"Chris," Aaron says with a laugh, "wanted one more holiday with his liver."

But Aaron and his wife, Laurel, will be back home in Ely, which is happy and unexpected news. On Dec. 6, 24-year-old Chris donated 58 percent of his liver to friend and bandmate, Aaron, who is 41. The two, who met through music four years ago, stunned their medical staff by walking out of the hospital less than a week later.

"Record speed," Aaron said.

They returned to the University of Minnesota Medical Center two weeks later to show their gratitude, playing a tear-inducing 30-minute set of their signature folk-rock music, then bringing levity to the staff by showing off their matching T-shirts: "I pooped today!"

The men met in 2009, when Chris was attending Vermilion Community College. He'd catch Aaron's gigs at an outdoor spot where Aaron played guitar and sang with a four-piece band called Crazy Neighbors. Chris, a mandolin player, "wondered if he could jam with us," Aaron says. "We haven't been able to get rid of him since."

Chris juggled school and gigs and graduated with honors. Aaron, a full-time musician and the father of five, traveled around the Midwest. A few years ago, Aaron started feeling like "something was off." He bowed out of a performance one weekend, but things didn't get better. Tests and more tests revealed that his liver was failing.

"It was a shock to everybody," he says. He wasn't a heavy drinker. "No war stories of younger years filled with boozing."

The band disbanded after that, and Chris returned to the Twin Cities. He'd check in with Aaron, "who wouldn't be all that forthcoming" about how sick he was.

"He kept bugging me every week," Aaron says. "He knew it wasn't looking good for me."

In January, Aaron told Chris he needed a liver transplant. One of Aaron's siblings, a cousin and a friend all stepped up to be living donors, but none was a match.

"You can't ask," Aaron says. "You don't ask people."

Chris, of Minnetonka, didn't need to be asked.

"Give me a number to call," he said. "I think it's going to be me. I had complete faith."

Chris got word that he was the match while working his landscaping job in early November. Preparing for surgery, Chris says they were both "kind of catlike." Aaron nods.

"I decided, 'I'll just do what they tell me to do and, eventually, I'll open my eyes and they'll say, You have a new liver.' "

After a 7½-hour surgery, he did. He felt amazing almost immediately, but it was upsetting to look at his friend.

"Chris went from being healthy to being hit by a truck," Aaron says. "It was hard to watch him struggling."

Today?

"He looks like Chris," a relieved Aaron says, noting that Chris' liver will regenerate.

Aaron will return to the Twin Cities for medical checkups. And the Crazy Neighbors?

"We're striking her back up," Aaron says. "But we'll cut down on traveling. We'll be the healthy band. It will be nice, actually."