The premiere of I Am Cait – the docuseries chronicling her journey as a transgender advocate – shows the first time Kylie, 17, saw Caitlyn's authentic self – and PEOPLE got a sneak peek at the touching moment during a screening in New York City on Tuesday night.
As it turns out, the encounter was a happy accident after Kylie FaceTimed Caitlyn from the dentist's office, admitting she was "kind of loopy."
"I don't want to scare you," a surprised Caitlyn, 65, said after answering the video chat.
"You're not scaring me," Kylie insisted. "You look pretty!"
Later, Kylie met Caitlyn in person at her Malibu house, joining her grandmother Esther and Caitlyn's two sisters.
"Hey, pretty!" she cried, running to embrace Caitlyn.
"Hey, baby! I didn't know you were here!" Caitlyn exclaimed.
Kylie had gifted Caitlyn teal extensions to match her own signature hair color, and she helped her dad weave them into her brown locks.
"Isn't this more fun than sitting around talking about sports?" Caitlyn quipped.
"Or playing golf," Kylie added.
"Well," Caitlyn said, laughing. "I wouldn't go quite that far."
In a voice-over, Caitlyn explained that her biggest concern had been how Kylie and Kendall Jenner would react to her transitioning from male to female.
"Once it was out there, they saw the support that I was getting, especially in the celebrity world," Caitlyn explained. "From Lady Gaga's little world to Miley Cyrus to Elton John. To see their support, I think it really made my kids feel, especially Kylie, that it's gonna be okay."
I Am Cait premieres Sunday at 8 p.m. ET on E!.