Gale is Katniss's hunting partner and closest friend from District 12. As Katniss tells us, he's "good-looking, he's strong enough to handle the work in the mines, and he can hunt" (1.34). The two characters have a good deal in common, from their backgrounds, to their family situations, to their shared harsh opinions on Panem's government. There's also some romantic tension simmering beneath the surface, but for now it has yet to come to a full boil.
Katniss's relationship with Gale is often contrasted with the friendly or romantic playacting she performs with Peeta:
I can't help comparing what I have with Gale to what I'm pretending to have with Peeta. How I never question Gale's motives while I do nothing but doubt the latter's. It's not a fair comparison really. Gale and I were thrown together by a mutual need to survive. Peeta and I know the other's survival means our own death. How do you sidestep that? (8.60)
References to Gale's character remind the reader that Katniss isactually capable of authentic emotion: friendship, love, and all of that good stuff – and not only emotion, but actual genuine happiness. She refers to Gale as "the only person with whom I can be myself" (1.12) and most of her happiest memories, she tells us, involve him (20.40). "Gale says I never smile except in the woods," she says (1.11). Of course, in the woods, she's always with Gale.
Though Katniss hasn't allowed her feelings for Gale to fully develop, it's clear that they are present. Gale mentions the subject of running away together, but Katniss sees this as something that, given their duties to each of their families, is impossible. "The idea is so preposterous," she says (1.26). So she doesn't stop to wonder whether it is a lack of feelings, or simply circumstances, that keeps them apart.
Gale is mostly absent in the novel and appears mainly in Katniss's many flashbacks or her interior monologue. He sometimes serves as a reminder of home or the unwanted voice of conscience:
I wonder what Gale made of the incident for a moment then I push the whole thing out of my mind because for some reason Gale and Peeta do not coexist well enough in my thoughts. (15.4)