Janine is an ordinary Housemaid who is a bit luckier than all the other girls in the house of Gilead. She gave birth to a baby. Therefore, other women are envious. The narrator knows her since being at the Red Centre.
It is soon revealed that Janine's baby is transformed to the "Unbaby," and it is taken away from the mother. However, Janine doesn't rebel. She is offered a higher position at the class of Aunts. She conforms to the situation and accepts the offer. That is why Offred looks down on her for being too adaptive. Janine symbolizes conformist's points of view at the society.
Janine in the Essays