Zack has known you since you joined Shinra and he became your mentor and roommate. He has known you for approximately four years.
He can't help but show you off to everyone, because you are the best student he ever had. He absolutely loves you.
If someone asked him what you reminded him of, he would probably say that you reminded him of a cute kitten, you had such an innocent appearance, and so adorable... and on top of that you were so short!
He saw you in the Shinra gym and soon a goofy grin appeared on his face, he approached while giggling and looked down at you, he grinned and quickly grabbed you by the waist and picked you up like you were a kitten easily.
"Awww.. you're so cute! You're mine now. C'mon, let's go!" He smirked and began to walk with you around while carrying you.