Nikki Wood's History
The Slayer
Nikki was born in 1955. She remembered that her mother used to say: "If you're gonna fight, fight outside." Nikki was eventually called as the Slayer in 1970 and trained by the watcher Crowley.
In the early 70s, Nikki followed her lover, Li, on a NYPD stakeout. He wasn't aware of vampires or Slayers, and Nikki discovered that the ring leader was a vampire called Le Banc, who was smuggling in vampires and a giant bat. Li was killed by a vampire in the conflict. Nikki later flew the bat, despite her fear of heights, until it died by crashing into an oncoming subway train. She then went after Le Banc to slay him in the Bahamas.
In 1973, Nikki participated in her Tento di Cruciamentum, much to the disapproval of Crowley, who was appalled that the Watchers Council forced her to undergo it as she was pregnant at the time. Upon surviving her Cruciamentum, she gave birth to her son, Robin. However, she did not know exactly who his father was as she "didn't take names when blowing off steam." Crowley arranged for Nikki to go into hiding and live a normal life with Robin. Nikki took her child and lived in South America as well as Mexico for a while. However, she couldn't dismiss her calling, and returned to New York and her duty as the Slayer.
Sometime in 1977, the vampire Spike tracked Nikki down, wanting to challenge and kill his second Slayer. They met and fought in Central Park for the first time with Nikki's young son Robin watching from behind a park bench. The fight came to a stand still and Spike fled the scene. Before he left, he complimented her coat. Following the battle, Nikki dropped Robin off at Bernard's apartment where he let Robin play with some "spooky doo-dads", telling her son that the "mission is what matters" as she had to go after the vampire.
Death and legacy
In the same year, Nikki and Spike had their final showdown inside a New York City subway train. Nikki was able to pin Spike to the floor and repeatedly punch him, but, as the train went through a dark tunnel, the vampire took advantage and switched positions. Nikki begged to be able to return home to her son, but he strangled her, before breaking her neck. After admiring her coat when they first met, he removed it from her body and wore it for the next 26 years until its destruction.
After her death, Crowley took Robin in as his own, relocating to Beverly Hills, and raised him to fight like his mother. In 2003, Robin moved to Sunnydale and teamed up with Buffy and her vampire ally Spike. While there, he learned from the First Evil, in the guise of his dead mother, that Spike was the vampire that killed Nikki.
Robin tried to get revenge on Spike by using the First's trigger to bring Spike's feral nature to the surface and fight the demon who had killed his mother. During the fight, Spike was able to recover from his own trauma and defeated him. Although, having regained his soul, Spike let Robin live, saying that he owed him for killing Nikki, but Robin wouldn't get another pass like that if he tried it again. Buffy, following up on the situation, warned Robin she would let Spike kill him, and told him, just like his mother, that the mission was what mattered.
Some time after the Slayer activation spell in 2003, the psychologically scarred Dana took on the personalities of past Slayers, including Nikki's. Since Nikki was killed by Spike, along with another Xin Rong in 1900, Dana perceived Spike as Walter Kindel, a man who kidnapped and abused her in her childhood. When confronting Spike, Dana mentioned having to look after Nikki's son, which caused Spike to remember Nikki.
Over a year and a half after the destruction of Sunnydale, Buffy believed herself to be pregnant after getting drunk at a housewarming party. Unsure of what to do, she turned to Robin for advice on how he handled being the son of a Slayer. Robin told Buffy that she was not Nikki and that he was confident that she could handle raising a child, because she had managed to balance a normal life with her Slayer duties, where most other Slayers, including Nikki herself, did not or could not.