The relationship between David Montgomery and Hunter Erb began with a wish.

In November 2017, Stephanie Erb emailed the Iowa State football program with a request. Her son, Hunter, who was 6 years old at the time, had been fighting for his life since birth, and it was his dream to score a touchdown for the Cyclones.

Iowa State coach Matt Campbell decided to invite Hunter to practice a few days later so he could fulfill his wish. Although Montgomery didn't know Hunter, the running back was Hunter's lead blocker on his run to the end zone.

"Once he scored, I got a thought in my head that God was pulling me toward him, and I needed to extend myself to talk to him more," Montgomery said.

Montgomery got in touch with the Erb family and went to see Hunter in the hospital while he was getting intravenous shots. Seeing Montgomery helped put Hunter at ease.

"You made it," Hunter said as Montgomery walked through the door.

"Of course, little buddy," Montgomery replied.

Hunter was crying from the shots, but Montgomery held his hand while the nurse finished. That's when their bond was solidified.

"Next thing you know, they are coloring in coloring books," Stephanie said. "To see this big football player, he's pretty much wrapped [around Montgomery's finger]. They connected. We say it was God's plan."

After accumulating 2,925 rushing yards and scoring 26 touchdowns in three years at Iowa State, Montgomery decided to forgo his final year of eligibility and enter the 2019 NFL draft. He is a third-rounder in Mel Kiper and Todd McShay's latest mock draft.

Montgomery's desire to help people was created by many things: how he was raised by his mother, Roberta Mitchell, his faith in God and a background in the Boy Scouts (Montgomery reached the rank of Eagle Scout, the highest rank). In college, he worked with children with special needs through Iowa State's Victory Day Initiative and was a semifinalist for the Jason Witten Collegiate Man of the Year Award. In Hunter's case, reaching out to help was a natural instinct for Montgomery.

Hunter encountered his first health issue a few days after he was born prematurely with multiple congenital heart defects. After twice being transferred to a different hospital, Hunter ended up at the University of Iowa children's hospital. When he was 1, he was diagnosed with pulmonary vein stenosis, a condition in which the veins that carry blood from the lungs to the heart become narrow. There is no cure, and Hunter was given a 3 percent chance to live.

David Montgomery visits Hunter Erb in his room at Mary Greeley Medical Center in Ames, Iowa. Courtesy of Stephanie Erb

The doctors told the Erb family to take Hunter home and love him during the time he had left. But there was no way the Erbs were giving up on their child, so they went to Children's Hospital of Wisconsin, where Hunter had his third open-heart surgery, even though the family knew his condition could reoccur.

In 2015, the condition resurfaced. The Erb family kept searching for solutions, which led them to Boston Children's Hospital and a study it was conducting using a chemotherapy drug. That helped Hunter's condition.

"You have to be a fighter," Stephanie said. "It's not an opt-out program. I believe God has a plan, but it may not always be our plan. You have to flow with it. It's one thing to say you trust God, but it's another to put all of your faith in Him to take care of things. As a mom, I take care of the possibles and trust God with the impossibles."

Now 7 years old, Hunter has a pacemaker and a heart stent, and his chest is wired together. But he still wants to play tackle football and do all the other things his peers do.

Stephanie credits Montgomery for being an outlet for Hunter to do some of those ordinary things. They motivate each other. They use FaceTime to talk every day. Montgomery even drove two and a half hours to visit Hunter in a hospital in Iowa City during finals.

David Montgomery holds a charm with Hunter Erb's heartbeat on it that was given to him by the Erb family. Courtesy of David Montgomery

Hunter gave Montgomery a bracelet that says "Team Hunter" on it . It's from when he was the Heart Walk ambassador for the American Heart Association's Iowa Chapter. The Erb family also gave Montgomery a charm with Hunter's heartbeat on it so he can always have Hunter with him. Montgomery says the Erb family has become a family away from home for him.

Roberta Mitchell invited Stephanie Erb to one of Montgomery's birthday parties. Like their sons, the mothers clicked immediately. Once they connected, the two families spent time together at every Iowa State home football game.

"It's the way it should be," Stephanie said. "It doesn't matter what you look like or what your background is. It's just people being people and loving each other for who they are."

The families plan to have a get-together in Cincinnati, Montgomery's hometown, during this week's draft. But the future NFL running back doesn't plan to be there -- he'll be working out instead.

Wherever Montgomery ends up playing his first NFL game, he'll have Hunter and the Erb family there to experience it with him. Montgomery led the way when Hunter got to fulfill his dream of scoring a touchdown during an Iowa State practice. Next Hunter will be there for Montgomery as he embarks on his dream of playing in the NFL.