Oksana Volkova is a dealer.
Cherny will play Oksana Volkova, a tough-as-nails, woman of big appetites and no apologies. She has close ties to the Russian mob in New York and controls the distribution of molly in Atlanta. Since escaping prison in Chechnya, the underworld is her natural habitat and she’s chosen the accumulation of power over personal relationships. 
She went to prison when she was 15 for 'stealing firewood' and got a commemorative tattoo.
She escaped from the Graveyard, a women's prison in Chechnya.
She used to sell Molly.
Oksana is introduced to Teresa by El Gordo. She vets Teresa and agrees to become her distributor for Atlanta. When Teresa believes that El Gordo attempted to kill her, she convinces Oksana to take her side and to organize a meet whereby Teresa kills El Gordo.
Oksana introduces Teresa her cousin Kostya, who runs NYC without Teresa actually meeting Kostya. Kostya agrees to buy from Teresa which results in her expansion to the North East.
Then the Judge kidnaps Oksana to force Teresa's hand, Teresa has no choice but to sacrifice Javier to free Oksana. Teresa values Oksana's friendship and business very much.
Oksana helps Teresa uncover who was behind the Russian kill team sent for her. Teresa and her team fly to Berlin to assist Oksana in recovering stolen molly from a deal done behind Kostya's back. Teresa sets up Oksana for an European expansion with Oleg's help.
When Teresa is forced by Devon to flush Kostya out and kill him, Teresa offers her business to Oksana if she kills Kostya as part of the plan to leave the business. As Kostya uncovers Oksana's betrayal, he poisons her in the last episodes of season 5.
- Oksana, to Teresa: Do you have your house in order?
- Oksana: They claimed it was because I stole some firewood but it was really because of my... proclivities.