This is super short but it's just something that popped into my head. Everything happens for a reason, sometimes those reasons happen when you wish for them.
"Come on Kate. Why don't you believe in magic?" Rick whined as he followed her around the bull pen.
"Because I just don't Castle."
"Don't or won't?" He continued to pester her as they walked into the precinct.
Beckett paused and considered her answer. "A little of both I suppose. I don't want to believe in magic anymore and I won't allow myself to believe in it."
"But why?" Rick asked stunned. "Wouldn't it be cool to be able to wish for anything you wanted?"
"What if what you wanted wasn't what was best for you?" Beckett retorted and watched as confusion entered Castle's face. "What if you made a wish today for something small and it had huge consequences?"
"Like I don't know, let's say your mother made it a rule that you have family dinner ever Saturday night-"
"My mother lives with me and she's rarely home on a Saturday night."
"This is hypothetical Castle. So your mom hypothetically wants to have dinner with you every Saturday night. You sometimes would rather go out with your friends or on a date. Pretty much do anything other than family dinner. So you make a wish one night to get out of having to do these stupid dinners. Next thing you know, your mom never shows up for dinner and you find out she's dead. No more family dinners ever again. Congratulations you got your stupid wish."
Rick was silent for a moment as he processed her story. "Oh Kate. I'm so sorry."
"Yeah well now you know why I don't believe in magic."