However, before they stepped out, Arlen's emotional story was shared in a pre-taped package, and it became clear that her journey to dancing on the show was more incredible than you could have guessed.
When Arlen was 11, she developed two debilitating afflictions that caused inflammation of her spinal cord and prevented her from moving, talking or even eating. She later fell into a vegetative state for four years, and doctors did not have high hopes for her recovery.
When she turned 15, she began to emerge from her vegetative state, and even started to regain some of her motor functions.
As her recovery progressed, she began to relearn how to walk -- a skill she didn't even begin to develop until a year and a half ago, after spending a decade in a wheelchair. Even now, she still can't feel her legs.
"I think this is a really big statement to myself, as well as to the people who wrote me off, that I'm here! I lived! And I'm ready to dance," Arlen said.
"I'm very excited to work with Victoria," Val shared. "She's the closest thing that I've seen to a living miracle. The fact that she can't feel her legs is a very small challenge compared to everything that she's been through."
As it turned out, her inability to feel her legs didn't keep her from delivering one amazing cha cha that truly blew away all the judges. Arlen herself couldn’t keep from crying tears of joy as she and Val finished their impressive dance.