Unfortunately for Lyda, she's stuck in the Dome for pretty much the whole book. And surprisingly, she doesn't play as big of a role as we thought she would. For the most part, she's been reduced to one role:
She's not Lyda. She's the vessel carrying a Willux. (5.22)
And Lyda is none too pleased about being reduced to a vessel. Because she's in the Dome, she can't be the warrior that she was in Fuse. Yes, she's still strong-willed and fiercely loving, but a part of her has been stripped away by the Dome's imprisonment.
Now, Lyda does rebel, and she still stands out as one of the dominant (or even the dominant) female characters in the last book. Lyda sacrifices her desire to marry Partridge by letting him marry Iralene instead. She does what's best for the Dome, making her a romantic martyr in some sense.
In a nutshell, Lyda doesn't belong in the Dome, and she realizes (a little too late) that the comfort and love of the mothers is actually all the love she needs. She loves Partridge, but her craving to be outside of the Dome burns brighter:
Lyda craves ash on her skin. She craves hunting in the woods at dusk. She craves the unknown rumble of a Dust—the earth trembling underfoot. (20.13)
Lyda's still our warrior — our pregnant, cooped up, stir-crazy warrior.