I don't think you've read Malazan, have you?
Have to second this. Especially Beak as a character. So childish, so whmsical...esp set in a grusome battle with tragedy looming over all of them. Probably one of my favourite segments.
*No, I deny tearing up...must be dust in air*G&G also works with gender roles. Grey is a human woman who dresses and “acts like a man” in a traditional patriarchal society. She is lesbian by tendency. Gurdig is a female goblin who also attempts to break out of traditional female roles in her society. This commonality is a key reason for the bond of sisterhood the two build.
I would advise caution on this. You don't really want to portray women who act like a man, but rather someone of her own strong personality. Not that I've read much, but the 'butch' characters seem to be more popular than the 'femme' characters whenever lesbian relationships are written in books
(I could be wrong in this though, but just a generic feeling). Breaking out from traditional feminine characterization is definitely not the same as acting like a male character imo.
But does whimsy have a place in G&G’s world? What are the preconditions for whimsy in a fantasy world, and how far on the continuum toward grim dark can you go with whimsy? Maybe its just a style of whimsy?
As to G&G world, why not? I'm not aware of any kind of partnership thatcan't be whimsical.
Now coming to Grimdark world, I'd definitely look forward. Whimsy serves to break up the darkness and balance the overall feel + it does enhance the grimdark elements. You've just lightened up and then wham! the death/grimness hits you twice as hard.