Brown-noser. Suck-up. Apple-polisher. Janine in The Handmaid's Tale. They all mean the same thing.
Janine shows up in the narrator's life during and after her time at the Center, and doesn't seem to have any friends. While the narrator knows Janine from the Center, the first time we meet her properly in the book is in her new role as Ofwarren, when she shows off on account of being pregnant.
The narrator instantly recognizes Ofwarren as Janine. Janine dealt with her time at the Center by kissing up to the Aunts; at confession times, she confessed repeatedly and with more gusto than anyone else. While she claims to have had an awful time in her pre-Gilead days, the narrator doubts her. Janine says "she was gang-raped at fourteen and had an abortion [...] It may not even be true" (13.18). Indeed, this information seems countered at another point in the text, when the narrator hears that Janine lost a baby when she was eight months pregnant, before the Center and Gilead.
At one point at the Center, Janine completely loses it, checking out and starting to speak as though she's her old self, a waitress. Moira has to slap her into consciousness. At another point Janine acts as an important ally to the other women at the Center by passing on information about what happened to Moira. Otherwise, the narrator wouldn't have known until she met Moira at Jezebel's much later in the story.
The narrator seems to find in Janine an object of both pity and revulsion. While she is in the same position as the other women at the Center, Janine seems to crave attention and behave differently from the others: "she had another child, once, I know that from the Center, when she used to cry about it at night, like the rest of us only more noisily" (21.18). Janine seems to cry "more noisily" than the other mothers who have lost children as if to outdo them, as if her grief is more real or important. The narrator seems to imply that by acting out her grief so loudly, Janine actually proved that it was less authentic than the others'.
Once she becomes pregnant with her Commander's child, poor Janine loses that baby too. Although at first the baby seems healthy, Janine will only be able to care for her for a few months before she's handed over to the Commander and his Wife and Janine is transferred to a new posting. But this new baby, Angela, doesn't make it. After everything Janine goes through, the baby is too imperfect to last.
The last time the narrator sees Janine is at the Particicution, where she has become completely unhinged: "Her eyes have come loose [...] she's in free fall, she's in withdrawal" (43.29-30). Janine can't handle this new reality, so she just checks out. Instead of sympathizing with her, the narrator is disgusted: "Easy out, is what I think. I don't even feel sorry for her, although I should. I feel angry" (43.32).
We can't say that we blame the narrator too much for her callous reaction.