Since We Were Five

Two best friends, Kayla and Zach, have been together since they were born. Literally. They were born in the same place, at the same time, and were next to each other in the cribs. Their moms were best friends of 25 years. They did everything together. It was like destiny.
But everyone knows nothing lasts forever. Zach moves away. He never stops thinking about Kayla. She was everything to him, even then.
Now Zach and Kayla are 15. She has an older brother named Cody, loving parents, and a best friend named Nicole. She even has a crush on the bad boy of the school, Carlos. But perfection never lasts long.
So what happens when Zach moves back and attends the same high school as Kayla? Zach is still crazy over her, but he doesn't admit it. Kayla finds herself thinking more and more about Zach, and the old times. Now, they're left wondering, was it destiny? Or was it just a cruel prank by the Fates?