It's pretty nice to have a breath of fresh air after all this LMM stuff. It was good, but I prefer more light-hearted writing in most cases.
Anyway, that was a pretty original mission, I kinda like the idea. (I mean, I'm not gonna use it because it kinda only works once, but still.) I'm not that fond of interacting with canons, but that's probably mostly because I can't write them right myself, and I actually kinda like how you do it.

First things first:

Even Gogo peeked out of here bag offered a "There, there."
Missing word "and"?

What has Sarah found there?

A transdimensional hopper who isn’t quite a Sue? Nah, that would be an original character.

A wraith who isn’t malevolent? Nah, a wraith would possess, not replace.

I’m tempted to write the story of this interdimensional traveler, lost between the worlds, until she found this one that looked like it might become home. She had a rather good time there. But finding this guy who was quite, but not really, like her, and shoving him out to take his place, had been a bad idea, so now she has to leave. While the world fades away, she knows that, next time, she’ll have to take a greater effort to fit in. But will she ever find another world where she can fit? Will she dare returning to this same world, in some distant place where nobody knows Hiro and will wonder why he suddenly looks like a girl? May she even be able to create a world of her own, and conjure all the imaginary friends she needs? Whatever she decides, Hiroko will be a good girl now.

I abstain; I certainly would embarrass myself with all the wangst and false emotions.

HG

Expectially after [REDACTED] happened to [REDACTED]. Then again, I have always been a bit partial towards missions where canons and agents interact more than "look this way, please!"

I mentioned you during the beta process: "Jack Frost hasn't been always the Guardian of Fun and the Spirit of Winter." And you left the canon hiccup in the mission.

Remember, according to the movie, before being a Guardian, he was a mortal, and according to the upcoming book The Guardians of Childhood: Jack Frost, before being the Guardian of Fun and the youngest of the Guardians, he was the Guardian of the Man in the Moon and the First Guardian, Nightlight.

And in before you tell me they're diferent canons, by Word of God (ie.: William Joyce), the movie is set in the same canon as the books, just 300 years later.

But it seems that you're collecting agents like a Trainer collects Pokemon! Are you sure that you're going to be able to juggle all of them?

Other than that, it's a pretty good mission, and a unique premise, i.e., an Agent interacting with a canon. So far, I recall only one error in the mission:
The blade clattered to the floor, it's icy chill dissipating.

P.S.: Have you received my e-mails?