Aurora, Colorado — Classes at AXL Academy in Aurora, Colorado, have been out over a week now. But for middle school math teacher Finn Lanning, there's one student he just can't shake, 13-year-old Damien. Damien said Mr. Lanning was definitely one of his better teachers.

"When a teacher doesn't bother me over and over again, that's better," he said. "Leave me alone, I'll leave you alone, I'll get my work done."

"He's smart and funny and he was always a student that stood out. Then one day he just came to me and said, 'I'm not coming back to school,'" Finn said.

Finn sat him down at a table and got an earful that day. He learned Damien was in foster care, that he had kidney disease and because social services couldn't find a foster family willing and able to meet his medical needs, Damien had to leave school and move into a hospital.

But here's the real kicker. The kid needs a transplant desperately and a lot of times you can't get a transplant if you don't have a stable home to return to after surgery.

"It hit me like a ton of bricks. I mean, you just can't sit across from somebody that you care about and hear them say something like that and know that you have room to help," Finn said.

That's how Finn became a foster parent. He took in Damien, dialysis needs and all, even though prior to that hallway meeting, he'd been a confirmed bachelor who delighted in his childlessness.

Finn and Damien CBS News

"I never thought that I could leave school and take one of them with me and still survive," he said.

Damien was right there with him.

"I was like, 'Yes! I get out of the hospital.' But I was like, my math teacher? Out of all the people," he said.

Now, six months into it, neither one of them would change a thing. Although Damien said he's not getting too excited just yet. He's seen fairytales fall apart before.

"It's kind of bad thinking about that but some people actually do that. Like, they'll be happy with you one day and just kick you out the next," Damien said.

"Whether he believes it or not doesn't change the fact that I'm not going anywhere," Finn said.

In fact, Finn said he plans to adopt Damien as soon as possible. In the meantime, and much more importantly, because of Finn, Damien got back on the transplant list and got his new kidney.

For a child steeped in disappointment, this is shaping up to be the best Father's Day weekend ever, a new kidney and a dad by his side. Although Finn said that dad title is going to take some getting used to.

"That role has such meaning attached to it, right? And it's not that I'm not willing to do it but it feels like you have to earn it, in some way," he said.

He's earned it and epitomizes it.

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