The style of Twelve Months makes me think it could very easily have had sections added or removed throughout the writing process. It doesn't have the hour-to-hour urgency of the typical stories, and Harry refers to stuff happening in passing that could easily have been a chapter or two or a whole adventure. So it's possible that depending on when you asked Jim, Cowl and Kumori were in the story to different degrees.

I honestly figured that's where the Bock's Ordered Black Magic storyline was going, I hear people talking about using Black Magic for moral purposes and I think "Kumori?" We've seen her playing antihero for random Chicago citizens before.

My best guess, and that's all it is:

There is a figure of speech I've heard often enough to think it's popular, at least regionally, "Shit weasel." Stephen King used it as the name of his rectally explosive monsters in Dreamcatcher.

I think "me-weasel" is an expression of Dresden's self hatred bleeding into his humor, as is common with seriously depressed people who crack jokes constantly. I have a brother who does this, he casually drops self loathing and suicidal ideation into his off-the-cuff banter, and I don't think it's intentional. I think it's something that feels so normal and correct that it bleeds through even when you don't mean it to, or even think about what you're saying. There's a reason people can pretend to be psychic and do mentalism tricks, most folks have no idea how much of themselves they're expressing.

Dresden takes it entirely for granted that Ramirez will know "me" means the same thing as "shit."

But that's just my impression. It could be that I missed something that makes it a callback. Just can't think what it would be.

I have a feeling Goodman Grey is going to become something of a regular. Harry needs two things these days: extremely powerful and durable allies, and beings with insight into remaining moral and using their power responsibly, while existing as something potentially monstrous and not fully free.