My personal choice: "Just, you know, things that happen, if they happen multiple times, one of those times has to be the first time. It's a law of physics or something." "There is no law of physics like that, Mulder."

Hahaha. I can totally hear them saying those lines.

First, a borderline-cheesy notion (the title makes even reccing this story kind of iffy) can be made excellent by attention to detail.

Hahaha. I know! I'm so brave! Reccing a popular holiday story by a popular author at Christmas time. The nerve!
But yes, very expert craftsmanship is evident, as always.

Sitcoms can be excellent but I maintain it takes more talent to write great humor than any other genre. Because great humor stays in character. Anyone with a sense of humor can write a decent joke. Only talent can make the joke sound like Mulder or Scully actually thought it up themselves.