Oh, it's them. That's obvious from the drawing on the front of the envelope, a scribbly depiction that's as good as the Postmaster General can get when it comes to words. It's clearly them.

But ah, the envelope . . .! They tear it open clumsily, stubby fingers tearing paper, only to find . . . a letter! Gosh! A very secret personal letter that they bring very close up to their face. Like, too close. How can anyone possibly read at that level of closeness is a mystery, but the Librarian seems to get something out of it.

They read . . . and read . . . and as they read, Kol will pick up something with those sensitive ears of his. A whine, so high-pitched ordinary humans might not be able to hear it, wobbling only occasionally. It's unending, one long single note, slowly growing louder the longer he listens.

Sooner or later, he'll realize it's coming from the Librarian. The noise keeps growing and growing, and hm, it's actually kind of painful now, it's actually really painful now, and maybe he'd best cover his ears because it's loud loud loud, it's unending, and even his sight seems to be blurring, or maybe that's just the Librarian shaking, vibrating at a frequency so fast it's hard to follow, it's--

Interrupted as the Librarian shoves the entire thing in their mouth. It's hard to see them doing it, but then again the paper is crumpled and disappearing in one, two, three bites.

Yum.

They sigh, then reach out to pat Kol's chest. Pat, pat. Well done, Kol!