Singer-songwriter Metal Mother is a purveyor of dark, synth-driven pop who made a name for herself in Oakland’s DIY warehouse party scene before relocating to Los Angeles to work on her forthcoming album. She describes herself as an “acid-drenched techno pagan” and fills her music with haunting vocal harmonies and distorted keyboard melodies that call to mind current left-field pop stars such as FKA Twigs and Grimes as well as earlier acts such as the Eighties industrial band Skinny Puppy. She returns to the Bay Area for her December 18 show at El Rio in San Francisco. Violent Vicky, another Southern California-based singer, shares the bill. While Violent Vicky has a similar penchant for ominous yet danceable sounds, her work is rooted in house and disco, with pulsating, four-to-the-floor beats that foreground looming synth lines and gritty, punk-inflected vocals. Her lyrics are often about seduction, but Violent Vicky uses her blunt humor to rail against capitalism and the male gaze.