Right from the start, from the opening line, Harry is whining. Thomas tells him he's going to be an uncle, and he's all scowls and aches. We get four scowls, a sneer, a glare, and threats of violence.
Harry finally thinks to crack wise at the end and -- starts coughing, and coughs for longer than he should need to.
Carlos shows up and *Carlos* uses humor to deflect the pain of his injuries. We get more scowling, and even a rare dialogue-tag adverb: Harry says something "darkly".
In Chapter 2 we get excellent humor with tons and tons of heart -- all of it from Maggie and Bonnie, while Harry plays straight man.
I get that there's lots of serious stuff going on with Thomas and Eb, but then Rudolph shows up. He's literally the perfect foil for some classic Dresden mockery, but instead Dresden goes directly to anger and threats. "Buzz off." "Or what?" What I expected Harry to say: "Or I shall taunt you a second time!" (in a faux French accent). Instead he's ramping up to "just try it" and broken noses.
He's a little better in the car with Lara and Mab, but still he's super jumpy with the shield bracelet and then he's mostly whining. Mab gets all the great lines in that scene.
Then Evanna tries to trade snarks with him, and his response is "Are you patronizing me?" It's like we're in a mirror universe where Harry is the straight man for everyone else's snarky wit.
Even when he's trying to be snarky it's flat. "Boy, tell me you ain't dumb enough..." "Oh, I'm more than dumb enough..." That's... that's not a Harry Dresden line. And Eb gets to be the snarky wisecracker with his repeated vampire lines, leading up to "See? Not one vampire needed." It's irritating that he keeps harping on the same topic, but it's Harry Dresden's own patented style of irritating snark.
Harry meets Freydis and tries to engage his snarky wit to let on that he knows she's a valkyrie, but it falls flat (because it's not clever, just insulting) and he ends up backpedalling it. He finally gets in his first Dresden-humor line of the book with "It's probably easier than replacing the landscaping." With Lara his best attempt is calling her an apex sexual predator, which is a cute phrasing but a bit too on-the-nose and gets less funny the more you think about it.
Heck, Sanya gets the single best joke in the book, when they're testing out the lightsaber. Epic-level joke. Harry doesn't laugh.
Dancing with Freydis... she's all snark, he's all business. And again he leaps to violent threats at the drop of a hat.
When he actually rescues Thomas, he finally starts to snark to himself: "I should make a cloak of levitation. Dr. Strange would never have this problem." and it's followed by: "I felt a flash of guilt at wasting time with smartassery and shoved it down."
Something is going on, whether it's the Winter Knight mantle pushing on him, or something even more insidious -- there's something inside him pushing him to lose the humor that's kept him sane in his darkest moments.
On the way to Demonreach, Murphy tries to start up the traditional tension-breaking laughs, but Harry's not in the mood. She has to make the Harry-deprecating joke for him, and he gives her half a laugh in response. ("Promise me you'll fight smart," I said. She bumped her head against my arm and said, "How would you know if I did?" I huffed out part of a laugh.)
Throughout the book, the best laughs Harry gets are *at his expense* when he says something unintentionally funny -- like when he asks Carlos if the White Council wants him to be Emissary or when he tells Murphy he feels very small.
Perhaps worst of all -- when Ethniu Sparta-kicks Mab and monologues, Harry is under the influence of his potion, and can't defuse the tension with inappropriate humor or rouse everyone with an underdog speech. He has to stand quietly and watch Marcone do it:"It would seem we have the Fomor's answer with regards to the peace process."