Kelly Sanbourne was once David Kim's most promising student, with a penchant for being late which earned her the nickname 'White Rabbit.' After she graduates, David hires her as his research assistant in the lab where he works, Organitek, studying nanomachines.
David and Kelly have a very close relationship, including intimate knowledge of each other, and frequent flirting. However, David is adamant that he is fully devoted to his fiance Dalila. Observations from other Organitek employees find their behavior indicative of a blatant affair, arranging dinner together and late night rendezvous, although this is disproven. David and Kelly are just very close friends, although not childhood friends. David does tell Kelly that he finds her very attractive, and that if he weren't engaged to Dalila, that he would 'ravish her on the spot.' It appears that the 2 do likely share some romantic feelings for each other, but decide to let them fall by the wayside so that David may remain faithful to his fiance.
Kelly's own romantic life is not as successful as David's, recently discovering her boyfriend was cheating on her for months with the woman who lived in the apartment next to hers.
All of this is rendered moot when the Rustling Husks break into Organitek to steal the nanomachines for Dr. Sugarman. While Kelly is in the bathroom, David is shot by a Rustling Husk, and when she returns she finds him dying in the lab. With his 'dying' breath, David asks her to inject him with the nanomachines programmed to his DNA. He also tries to tell her that if it doesn't work, she should deliver a message to Dalila, but he is unable to finish his sentance. It Is assumed he wanted her to tell Dalila that he loves her. As she waits for the process, Kelly hugs David, but it's stated that it was more for her own comfort than David's. As David awakens, he is horrified to discover that a huge chunk of Kelly's body was used by the nanomachines as raw material to repair David. The arriving police believe David intentionally harmed not only Kelly, but the other members of Oraganitek. His name is later cleared by Nun of the Above.
After foiling Dr. Sugarman, David makes a failed attempt to resurrect Kelly.
Kelly death continues to be one of the greatest driving forces for David's character development. Her death is essentially the symbol of the death of David's normal life. David will likely always feel a degree of remorse for Kelly's death, but he doesn't let it define him. He is constantly pushing forward to put the past behind him without letting himself forget it.