"To all you rockers out there in Termina! Many thanks for coming out to see our gig!"As mentioned on the front page, Chrono Cross is 2000 sequel to 1995's Chrono Trigger, but it's more a continuation in spirit than in plot (although a few characters from the original do appear in small roles). When the main character Serge wakes up and realizes that the world he's now in is not his own "Home World," in true RPG fashion he doesn't just sit on his laurels but tries to do something about it. Along with a young thief named Kid he meets in the alternate "Another World" he quests to find out the truth, which turns out to be closer to him than he could have ever known. Near the beginning of their travels, Serge and Kid decide to sneak into Viper Manor, and go in search of someone who can help them, and one of those someones just happens to be Nikki.
"Another World" Nikki
The son of the pirate Fargo and the mermaid Zelbess, Nikki's mother died when he was young and he was subsequently separated from his father and his younger sister. He grew up to be a famous bard with the performing group the Magical Dreamers, but he never forgot about his missing family. When his group travelled to Termina he used the opportunity to search for his sister, suspecting her to be somewhere within Viper Manor.
Miki, a dancer in the troupe, enlisted Serge and Kid to help her retrieve Nikki, who had wandered off into the Shadow forest. They agreed, and when Serge and Kid entered they found him trying to sneak into Viper Manor to find his sister. Having a similar goal, they joined forces.
"You... You look just like... mother... There's no doubt about it. You're my little sister!"
Within the manor he came face to face with Marcy, one of the four Dragoon Devas, and instantly he knew her to be his missing sister. She remembered nothing of her family, however, and fought with the three of them before running off.
After the trip to Viper Manor reaches a conclusion, the Magical Dreamer's performance is postponed indefinitely and Nikki is free to remain in your party. At this point his story is pretty much put on hold.
His story picks up again once you board the ghost ship. Once things calm down on the pirate ship Nikki realizes that the name is the S.S. Invincible, a name he remembers from his past, and he asks Fargo if he has any children. Fargo replies that his children are dead, not knowing that they are in fact alive and his son is standing right before him. The game, however, leaves you hanging, which seems to be a common theme for the Nikki from Another World.
"Home World" Nikki
When Serge finds himself stuck back in his home world he encounters another Nikki, whose life was very similar to the one we're familiar with one difference: this Nikki has been hired by Fargo (unaware that Nikki is his son), along with the rest of the Magical Dreamers, to perform on his cruise ship the S.S. Zelbess. As well, in this world Nikki is the last hope for the demi-humans, as he is the one who can sing the song needed to heal their island of Marbule.
The fact of the matter is, Marbule is riddled with unseen monsters, and the song actually has the power to reveal them so that Sarge & Friends can go in and fight them off. Zelbess' sister Irenes desperately tries to get Fargo to let Nikki sing the song, and Nikki takes the cause as his own and also tries to convince the man he realizes is his father.
"The gentle and caring father I used to know!? You're my father, aren't you!? But why are you participating in such dubious acts!?"
What it takes to talk sense into the embittered Fargo is himself from Another World - a Fargo that never stopped fighting. Home World's Fargo relents, and Nikki performs the song of the demi-humans while Sarge finishes the job.
Sadly, that pretty much ends Nikki's contribution to the plot in both worlds.