Grandma Sorenson has been mysteriously absent for some time now, and she wasn't even at the funeral where Seth and Kendra's mom pestered Grandpa Sorenson to watch the kids for a few weeks. And of course, when the kids show up, she's still not there. What's going on here?
With all the craziness of Midsummer Eve, the kids put the question on the back burner… until they return to the house after looking for Grandpa and Lena and find a message written in their pet chicken's (Goldilocks) feed: "I M GRAM" (13.34-35). Yup—their grandmother has been turned into a chicken.
As a chicken, she can't speak and can't focus for very long, so with a series of nods for yes and head shakes for no, the kids confirm that she's their grandma and that they need to take her to the witch to disenchant her. When Grandma's restored to her body, she's a little on the short and curvy side, "with hair the color of cinnamon and sugar" (13.169)—we can't help but like her immediately when she's described this way.
Being a chicken was apparently a strange experience. The way Grandma explains it:
"As a chicken, thinking clearly becomes an exhausting challenge. My mind was in a haze. To interact with you like a person, even for a moment, required tremendous concentration." (13.190)
This makes sense, we suppose, since chickens aren't exactly the most intellectual creatures in the barnyard. Grandma opts not to tell the kids exactly how she got turned into a chicken though, saying only: "Pride made me careless […] Let's save the details for another time" (14.10). Our guess is that she's embarrassed at having been transformed against her will, and doesn't want to tell the kids about it if the topic can be avoided—or perhaps it's just a story for another time (or, as the case may be, book).
Right from the moment that Grandma's back to herself, she starts taking care of business. She tries to evict Muriel (who's now free) from the preserve, but without success, and next up on her to-do list is locating Grandpa. Apparently Grandma is a toughie since she doesn't need long to get re-oriented to being human after her time spent as poultry.
And indeed, Grandma takes the kids to meet Nero, driving a bargain to ensure that they'll get the intel they need to find Grandpa. This in fact involves a bit of bluffing: Grandma convinces Nero to trade the info for a massage, which she makes seem like a big deal by acting like she's giving away something very dear: "Grandma wrung her hands. She folded and unfolded her arms. She rubbed her brow" (14.159). Pro tip: Don't play this lady in poker, because she's an excellent bluffer.
Grandma is really practical, too. When Seth tries to wallow in guilt and self-pity over his role in the Midsummer Eve debacle, Grandma tells him, "'Let's worry about fixing the problem instead of the blame. Don't despair. I know we can set things right'" (15.69). Yep, she definitely sounds like a glass-half-full kind of person, and also inclined toward kindness. She's willing to try to kill Muriel to stop her from releasing Bahumat, but it's very much a last resort (and she misses her shot, anyway).
Grandma gets captured after this, and then released again by Kendra's fairy army. She has to spend some time in between her capture and release as a slug, which is pretty gross—but we're guessing it still beats spending months and months as a chicken.