NEW YORK -- CW will use its biggest hit, "The Vampire Diaries," to launch this fall its first crunchy-gravel period drama. And the network's most successful freshman drama, "Arrow," will be used to launch a series about teens who have supernatural powers."The Vampire Diaries" spinoff, "The Originals," will not be paired with the mothership show on Thursday nights, as you might expect. Instead, "The Originals" will kick off CW's Tuesday nights and be paired with those still-kicking demon-hunting brothers of "Supernatural."And that crunchy-gravel drama, "Reign," will get the "Vampire Diaries" lead-in because "Vampire Diaries" is the CW's most-viewed series among young chicks.