Vanessa was created by George Perez, and she first appeared (as the Silver Swan) in Wonder Woman vol. 2 #171, August 2001.
Major Story Arcs
Vanessa 'Nessie' Kapatelis had the chance to meet Wonder Woman at a young age. When Wonder Woman first came to the United States, Nessie's mother, Julia, invited her into their home. At first, Nessie was jealous of Diana's beauty, but eventually the two got to know one another and formed a close bond, with Nessie loving Wonder Woman as an older sister. Only a high school student, Nessie dreamed of fighting evil alongside Wonder Woman.
Nessie had already been traumatized by her father's death when she was a child, but she was pushed over the edge when her best friend Lucy committed suicide. She began to blame herself for all the bad things that happened to the people she cared about. Doctor Psycho began causing her to have nightmares and, to help Nessie recover, the school counselor recommended that Wonder Woman leave the Kapatelis house.
Nessie recovered, but could not forgive her mother for making Wonder Woman leave. Eventually, she would start to blame Wonder Woman for abandoning her. Circe, in conjunction with Doctor Psycho, decided to use these mixed feelings as a way to use Nessie against Wonder Woman. Employing cybernetic implants and mental conditioning, they turned the young woman into a killing machine - the new Silver Swan.
After defeating Circe, Wonder Woman tried to help Nessie recuperate. However, Sebastian Ballestros, who had been behind Nessie's initial transformation, kidnapped Nessie and sold her to Veronica Cale, a woman who hated Wonder Woman. Cale ravaged Nessie's body even further, making her her even more of a cyborg and sending her to fight Wonder Woman once more.
Defeating Nessie again, Wonder Woman begged Dr. Leslie Anderson to remove Nessie's cybernetic implants once and for all. Nessie was then sent to Themyscira for recovery. It is presumed that after Themyscira vanished, Nessie returned to the care of her mother.
Vanessa has recently graduated from school. Wonder Woman as Diana Prince attended her graduation. They took some time for a quiet chat. It looks that all three Silver Swans no longer have the power or yearning to become the Silver Swan.
She has not appeared in the New 52.