KNOXVILLE, Tenn. — Hundreds of families had Zoo Knoxville all to themselves tonight for Dream Night at the zoo. 

The zoo invited kids from East Tennessee Children's Hospital to see their favorite super hero, get a face painting and see the animals, of course. 

Dozens of families attended the event and they all had something in common: There's a young person in their life that is dealing with a life changing condition. 

"Some of the symptoms are seizures and upper respiratory infections," Sonya Long said. 

Cortlan has Rett Syndrome, and his mom, Sonya, said most boys with this disease don't live past two years old. Cortlan has defied those odds and is now seven. 

Four-year-old Veronica was diagnosed with leukemia just last year. Her mom said it's been a battle and it's hard to answer all of her questions. 

"When she asked me if I still loved her even though she didn't have hair, that was the hardest part," Jessica Apolinar said. 

Zoo Knoxville invited patients from East Tennessee Children's Hospital to include them in what is a regular outing for many other kids.

"It just blesses my heart to see her be normal. It's something you wish you could see in the very beginning when she couldn't go out," Jessica said. 

Cortlan and Victoria are a few of many children unknowingly making their parents happy, just by being happy themselves. 

"When we were at the gate getting in we saw the Storm Troopers, and at that point, it made my heart melt because he was so excited and happy. It's the best thing in the world," Sonya said.  

A day filled with superheroes and snakes can make any child and parent forget about their struggles. 

"Just to see him happy is all that matters to me," Sonya said. 

Veronica's visits to the hospital are slowing down, but she still gets chemotherapy every two weeks. 

Cortlan's condition can't be cured, but treatments can help with the symptoms.