Nikki is a young, Caucasian woman with long, brown wavy hair. She wears a sleeveless yellowish green top underneath an unzipped, pink long-sleeve jacket atop a set of short bluejeans with what appears to be brown shoes.
She is an unstable individual who can react violently, due in part to her meth addiction. This is seen clearly when she learns about Johnny's syphilis and multiple partners, and ends up killing him. Even after she kills Johnny, she has hallucinations that she is still in the hotel with him, talking to his dead body.
She first met Johnny Rose in high school and began a shoplifting crime spree with him before the fourth season where she was eventually caught with Johnny and later testified against him for a reduced sentence. At some unknown point in time Johnny and Nikki rekindled their romance and made a plan to rob people so they could buy a boat and sail off into the sunset. They would later become famous for these crimes as they tended to target tourists, thus earning them the nickname "The Vacation Robbers".
- "Living the Dream" (not seen)
This series of robberies escalate to murder after one of their victims interrupts them and is incidentally killed in the struggle. After this, they change their way of operating, beginning a new spree that includes killing. They begin to be referred to as the "Vacation Murderers".
- "Remains to Be Seen" (not seen)
They commit another murder and steal every thing they can carry. The law identifies them after Johnny accidentally cuts himself on a cactus, leaving blood evidence.
They are suspected of gunning down Frank Lundy and Detective Debra Morgan with Lundy dead and Morgan alive. Sergeant Batista takes advantage of a reporter, Christine Hill, by telling her about Johnny's syphilis and multiple partners in an attempt to cause a rift in their relationship. When Nikki sees the news article, she overreacts and ends up killing Johnny and hallucinating until she is eventually tasered by Detective Joey Quinn in a back alley.
Nikki confesses to the Vacation Robberies and Murders, but not to shooting Debra and Lundy. Debra confronts Nikki in jail about the shooting, and threatens to lie and say that she saw Nikki that night. After a long back-and-forth, Nikki convinces Debra that she had nothing to do with Lundy's murder. It is presumed that Nikki is sent to prison as she is never seen again.
- Johnny Rose
- She and Johnny kill two people during robberies,.
- "Living the Dream" (killing spree only; not seen)
- "Remains to Be Seen" (killing spree only; not seen)
- "Blinded by the Light"
- "Dirty Harry"
- "If I Had a Hammer"