Finn Lanning was single and enjoying his bachelor lifestyle when 12-year-old Damien walked into his life — and never left.

The math and science teacher at AXL Academy in Aurora, Colorado, had been teaching for seven years when his seventh-grade student told him in 2018 he wouldn’t be returning to school after Thanksgiving break.

Damien told Lanning, 37, he had focal segmental glomerulosclerosis, an autoimmune disease that had seriously damaged his kidneys.

The preteen began showing FGSG symptoms, such as swelling and difficulty walking, when he was around 7 or 8 and wound up in foster care after his mother lost her parental rights because she was unable to manage his medical needs.

“He told me he had to leave the foster home he was living in and was moving into the hospital because they didn’t have another place for him,” Lanning tells PEOPLE in this week’s issue. “I remember kind of sitting there with him and not really knowing what to say.”

Bounced from home to home, Damien also spent months at a time living in hospitals because of his illness. He was in desperate need of a kidney, but because he didn’t have a stable home environment, he was taken off the transplant list.

© capturedbymarcela.com "He was literally living alone in a hospital because there was no place else for him to go," says Finn Lanning about his soon-to-be son Damien

RELATED: 10-Year-Old Girl Dying of Kidney Disease to Receive Transplant from Teacher

“He was getting passed around to different people who offered different levels of care with long periods in-between of literally living alone in a hospital because there was no place else for him to go,” says Lanning. “He’d have a nurse who took care of his health and that was his life. I’m surprised he managed as well as he did.”

When Damien had to leave school, Lanning didn’t think twice about what he wanted to do. The teacher began to visit his student at the hospital, and during Christmas break, made the decision to foster him.

He began intensive training on how to administer the boy’s daily 12-hour dialysis and was “shocked” when he learned just what that consisted of.

“It’s a lot scarier and riskier than I thought,” says Lanning, who made sure to provide for the rest of Damien’s needs, as well, including stocking up on the correct kind of toothpaste and scheduling his doctors’ appointments.

© Provided by People Go Fund Me Finn Lanning and Damien

“I’d really thought a lot about this decision,” he adds. “I didn’t want to be another person in a long line who’d made a commitment to him and then couldn’t keep it. I wanted him to trust me and feel comfortable.”

For more on Finn Lanning and Damien, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribe now.

Now in the lengthy process of adopting his former student, Lanning and Damien both wouldn’t have it any other way.

“I’m grateful that Finn has helped me have a place to live, make friends and enjoy my life,” says Damien, who couldn’t wait to start swimming again after getting back on the transplant list and successfully going through with the surgery in June 2019.

Adds Lanning, “It’s the simple things we enjoy doing together. I never thought I would end up being a father. I feel very lucky.”

Together, the pair enjoy cooking together (crab and shrimp boil is a favorite), and on the weekends they typically head to the movies or the arcade.

A GoFundMe page has helped Lanning all along as he provides for Damien’s daily expenses and takes time off from work to care for him.

They spent this past Christmas with Lanning’s family in Wichita, Kansas, where Damien sang karaoke for the first time.

“You kind of lose hope after a while when you’re living in the hospital,” admits Damien. “But now, I can settle in, go to school, make friends and live a good life. It changed my perspective on the world. Now, I can do anything.”