Roseanne set the standard. My So-Called Life pushed the envelope. But the trend away from wholesomer-than-thou prime-time progeny can always use fresh blood. As the off-kilter offspring on Cybill (the CBS sitcom starring Cybill Shepherd), Alicia Witt and Dedee Pfeiffer are this year's most promising donors.
While Cybill's writers may be responsible for the realistic now-allies/now-enemies dynamic between brooding, deadpan Zoey (Witt) and her supremely uptight married sister, Rachel (Pfeiffer), it's the actresses' off-camera camaraderie that gives the characters depth. ''Dedee's like the big sister I never had,'' says Witt, 19, a piano prodigy who began reading at 6 months and earned her high school diploma at 14, after being educated by her parents at her Worcester, Mass., home.
''I adore her,'' agrees Pfeiffer, 31, real-life kid sister to Michelle, and her California family's ''Auntie-Mame-like oddball out.'' In addition to sharing a mutual O.J. trial obsession, ''Alicia and I have these unbelievable emotional/psychological/professional/intellectual/spiritual conversations.''
Both Pfeiffer and Witt are big-screen bound later this year: Pfeiffer in the drama Up Close and Personal, with Michelle and Robert Redford; Witt in the Allison Anders segment of Four Rooms, as Madonna's juvenile-delinquent lover, and in Mr. Holland's Opus, as a ''wallflower music student.'' To prepare for the latter part, Witt, true to her overachiever nature, learned to play the clarinet too well: ''They had to teach me how to squeak on cue.''