So in Wonderland, that mysterious invisible figure was communicating with Magnus through Thieves’ Cant, right? And that figure ended up being Barry. Meaning at some point, extraplanar researcher and overall nerd Barold J. Bluejeans learned thieves’ cant. Did he get into trouble at some point and got pulled into a thieves’ guild somehow? Or was Barry’s case more like:

Bad News: Our team needed to convince a group of rogues that we were trustworthy.

Good News: We didn’t have to go on some kind of elborate sidequest to earn their trust.

Bad News: My boss finds it very concerning that I know Thieves’ Cant, and tried to unlock my Tragic Backstory™. I was too embarrassed to admit that the reason I learned was because, at thirteen, I figured that was the kind of skill that would impress cute girls.

Good News: A cute girl saw me do it.

Bad News: It was Lup, and since she’s already seen me fall out of several trees, cry because I saw a fawn that was just too damn small, and knows I can ride a unicycle, she’ll never think I’m cool no matter what I do. It’s too late. She knows.