The motif of the sky is a reoccurring symbol throughout Zack and Aerith's relationship, especially in relation to Crisis Core. When Zack meets Aerith for the first time, she offers to escort him to the entrance of the upper plate. On their way there, Zack, being the character who likes cheerful environments, notices how gloomy it is under a plate without a sky. Aerith claims that she doesn't like seeing the sky-- she tells him that she feels like it's sucking her in. Granted, with all the pollution surrounding the Midgar metropolis, a place where she's lived since she could remember, it's no wonder why she wouldn't like the sky.

"One day, I'll take you to see a beautiful sky, the real sky. It's not frigtening at all. I know you're gonna love it"
      -- Zack, Crisis Core: Chapter 5

While Aerith's attitude is much more disheartening, Zack's viewpoint of the sky is far different from hers; he looks at it as a gift from nature, a place where the heavens are. Being a member of SOLDIER offers lots of traveling privileges, and Zack has seen much more the world has to offer than the 17 year-old Aerith. He wishes to show her the majestic sky that he knows, and believes that it shouldn't be something to fear, but something to love. After all, you can't really love what you don't know. Coincidentally, just as she learns to love the sky she once thought was horrible, she learns to love a SOLDIER, something that she also wasn't too fond of.

During their date at the park, Aerith notices the color of Zack's eyes, which she deems has his most attractive attribute. He remarks that they're just like the color of the sky. Aerith, knowing this, says if those were indeed the sky, she wouldn't be in fear of it anymore. Although he would never be able to keep his promise and take her to see the sky, he offers her something else much more rewarding.

"If it's that sky I'm looking at, then I'm not scared at all."
      -- Aerith, Crisis Core: Chapter 5. English translation of the Japanese script

While on the brink of death, Zack's last words include the thought of a girl who was "afraid of the natural sky", and wondered why she first disliked something so pleasant. In the epilogue of Crisis Core as well as in the opening events of Final Fantasy VII, Aerith is shown selling flowers above the plate, as Zack first suggested. She finally gathered the courage to go up above all by herself, closer to the sky, where he had wanted her to be.