Nicole and Michael Draper always loved the idea of a big family. They started seven years ago with the arrival of their daughter Caitlin. Twins Emma and Brendan arrived in 2001.
In early 2005, with another pregnancy under way, the Phoenix couple received more good news at the doctor's office. They were expecting another set of twins.
A month later, doctors spotted trouble in a routine ultrasound: a condition called dilated cardiomyopathy, meaning a heart too weak to do its job. The condition is rarely diagnosed in utero, and it is rarer still for each twin to have it.
"The fact that both of them had it was just amazing to them [the doctors] as well as to us. The word that the cardiologist used was 'unfathomable.' He said, 'It is unfathomable that both of these babies have this condition,'" Nicole Draper said.
Her pregnancy became an escalating medical suspense, peaking on the day she delivered. As her husband, Michael, described it, "Everybody was tense. Everybody. There were eight or nine people in there."
In front of a crowd of anxious doctors, Nick and Nathan Draper came into the world on the morning of July 11, 2005. They were immediately rushed to intensive care and within hours the boys were on 10 different medications.
Soon after the twins were born, complications mounted.
They were moved by ambulance to Phoenix Children's Hospital where heart specialists advised having the boys flown to the University of California in Los Angeles, the closest place with the expertise to keep them alive.
"It was terrifying to receive the news that they had done so poorly in that first 24 hours," Nicole said.
When they arrived in Los Angeles, they were greeted with even worse news from doctors.
The Drapers were told that both babies needed heart transplants within three months to six months -- and that the wait for scarcely available infant hearts could often be longer.
"It was devastating to me," Nicole said. "We just kept hearing so much negative information."
A positive moment came when a nurse told Nicole she could actually touch her babies for the first time. "We were very grateful for every moment that we had," Nicole said.
Nate was in the most critical condition. Beyond his heart problem, he'd developed a small bleeding in the brain.
"I don't know how many people told us that he wasn't going to make it," Michael said.
With the Drapers' babies awaiting heart transplants, the Mattell Children's Hospital at UCLA became the center of the couple's lives.
They moved into a Ronald McDonald House with their other children and for months Michael traveled back and forth to his job as an enrollment counselor at the University of Phoenix. The twins went through constant medical ups and downs.
After almost four months, Nate became strong enough to leave the hospital. About seven weeks later, his condition worsened and he was readmitted.
Nicole remained optimistic, even though her hopes for a transplant would mean another baby would have to die.
"We don't want bad things to happen. We would never wish that," Nicole said. "We just hope that if something bad were to happen, that someone would consider organ donation and consider having something good come out of something very difficult."
No one could have known that a heart for Nick was then beating in the chest of an infant in Florida.
In Panama City, 7-year-old Mariah York's parents had been trying for a long time to give her a brother or a sister. Last fall, it finally happened.
"What a gift it was, and what a miraculous thing it was that had happened," Tracey York said. "He just lit up a room with a smile."
On a typical day last February, Mariah went to school as Tracey went to her waitress job and her husband, Russell, was working as a cook at Applebee's. Baby Jordan was left with his grandparents.
Roughly two hours later, in the kind of life-shattering accident all parents fear, Jordan suffocated underneath a pillow.
Hours later, doctors told the Yorks that their "miracle baby" -- the child they had tried to conceive for five years -- was brain dead. "There was just nothing that could be done," Tracey said.
They were then asked to consider donating Jordan's organs.
While the Yorks were deciding, the Drapers were entering their seventh month of waiting for an infant heart. It was Valentine's Day, and they were about to be connected to another family in ways neither could have imagined. The Yorks had said yes to donating Jordan's organs.
For Russell York, the decision was a way for his son to "live on" despite the tragedy.
'They Have a Heart for You'
The following day the Drapers received the news that 7-month-old Nick was getting a heart.
"To be quite honest, I was scared," Michael said. "This is the big surgery. This is it. There's nothing bigger."
The surgery was to be performed by Mark Plunkett, a surgeon with a successful track record and a full appreciation of the risks.
"This is someone's little boy. The stakes are high because the rest of his life is hinging on what we do here," Plunkett said.
Just after dawn on Feb. 16, Jordan's infant heart arrived at the UCLA hospital, raced from the airport by helicopter.
In a tense moment, the Drapers walked Nick to the surgery. "You are handing your son over and you don't know the outcome," Michael said.
When the surgeon opened his chest and removed the ailing heart, the defects were instantly apparent. When the healthy heart was implanted, it started to beat immediately. About four hours into surgery, the small heart became sluggish and the heartbeat was erratic. "I was sweating bullets at that point," Plunkett said. "Obviously this was a horrible problem."
"This kid goes through eight months of never going out of the hospital, and you're going to tell me that some other child had to pass away and gives up his heart and then we are going to have a problem now?" Michael said. "This can't be the way this plays out. This is unimaginable."
Progress, at Last
The doctors told the Drapers the next 72 hours would determine Nick's chances for survival. Immediately after his transplant operation, it was life support machinery -- not his new heart -- that was keeping him alive.
Three days after the surgery, doctors noted a remarkable turnaround. "It was just absolutely amazing to us that the little heart was beating almost normally inside our baby," Nicole said.
"He now has the opportunity to sort of grow and develop normally," Plunkett said.
Now the family waits for a heart for Nate. Doctors first said both boys would need new hearts within three months to six months of birth. Nate is already two months past that deadline.
For now, the Drapers are taking things one miracle at a time. Last Saturday, baby Nick came home with the family to their accommodations in UCLA's Tiverton House, which offers housing to families with patients under the hospital's care.
They remain grateful to the family that enabled this moment.
"We stand in awe of them," Michael said. "And you know little Jordan, you know he saved Nick. And, we'll always, we'll always remember Jordan."
In a highly unusual decision for families on either side of a transplant surgery, the Yorks and Drapers decided to meet in person. Watch these two families, joined by two children, meet for the first time on "20/20."