Like Fiona, he was born prematurely. Their meeting will melt your heart.

Since Fiona the hippo has been on display at the Cincinnati Zoo & Botanical Garden, she's had thousands of visitors come from all corners of the country to say "hello."

But not all of them share a bond with her quite like Calvin Underwood.

Just like America's favorite hippo, Calvin's life began early and with multiple medical problems, according to a video from the Cincinnati Children's Hospital.

And, much like Fiona, the 4-year-old had a special care team at Cincinnati Children's for the first few months of his life.

More: The story behind Fiona the hippo's survival

More: These inspiring cards children sent to Fiona will make you weep

"He loved to be held, I remember holding him and calming him and just he loved to be up close," said Darci Clark, who was among the nurses who cared for Calvin when he was born.

The care Calvin received at Cincinnati Children's following his birth is what the NICU nurses strive to give each of the premature babies that come through the unit.

"Taking care of these babies here, I always look at it as when they are in my care I treat them like my kids, like how I would want my kids to be treated if they were here," said Ashley Simon, RN. "It's not all just medicine and it's not all just an assessment. It's what compassion do you give to that person? Because that's another human being."

And that care is what Calvin's family says made him the "lovey and snuggly and happy" boy he is today.

"We kind of refer to the nurses in the NICU as his first moms," said Brittney Underwood, who fostered, and eventually adopted, the 4-year-old.

Now, Calvin is happy, healthy and thriving — just like Fiona. And like the thousands before him, he recently visited the zoo to say "hello" to his favorite zoo baby.

Calvin stepped up to the glass, watching Fiona porpoise around Hippo Cove with her mother, Bibi.

Then, Fiona swam up next to him and stood there as he blew her kisses.

It was as if she felt their bond. Maybe she did.

Watch the full video below.