ABC's One Life to Live introduced daytime's first story line about campus gang rape last year and hit paydirt with it at May's Daytime Emmys. Awards went to OLTL for Outstanding Writing and to actors Hillary B. Smith (Nora, the defense lawyer), Susan Haskell (Marty, the victim), and Roger Howarth (Todd, one of the rapists). In recent weeks, however, the usually conscientious show has slipped into the disturbing soap trend of reforming its villains into good guys (Todd rescued Marty from a car wreck and sweetly befriended two kids). Howarth has proven to be immensely popular among viewers thus the writers' dilemma. But the actor is fighting the reversal: ''He is not going to be redeemed. The people at One Life are not going to screw that up.'' Hope he's right.