Queen Arachnia was the Queen of the Spider People in Tom Paris' holodeck program The Adventures of Captain Proton. Photonic lifeforms mistook the program for reality and believed that they were about to be invaded by Doctor Chaotica. Janeway played the part of Arachnia so she could deactivate Chaotica's lightning shield so Captain Proton could save the day and convince the aliens that the threat was gone.
She charmed her way into Chaotica's Fortress of Doom. Arachnia was going to release her irresistible pheromones which would allow her to control Chaotica. He told her that he would lower his shields to allow her ships to join forces with him only if she agreed to be his wife. He became suspicious, and she was forced to pull a ray gun on him. Chaotica then orders Lonzak to shoot Arachnia but it proves futile (in reality, this was because the holodeck safety protocols were on, meaning the photonic weapon was harmless to Janeway, but she played it off as if Arachnia was impervious to ray guns). So, he trapped Arachnia in his confinement rings (force field), and promised that he would not kill her until after their wedding night.
Arachnia released her bottled pheromones which lured Lonzak, his head guard, into setting her free. Arachnia then shoots Chaotica's servant, and forced him to lower the shield, she then shoots Chaotica. (VOY: "Bride of Chaotica!")
Later, she was forced to again charm Doctor Chaotica in hopes to prevent him from using his death ray on her. She was forced to woo The Doctor into her arms, and distract him to uncover the "science panel," which housed some circuitry from the USS Voyager. (VOY: "Shattered")