For the past 40 years “The Omen” movies and their collective stories about Damien Thorn, a.k.a. the Antichrist, have terrified multiple generations of horror fans, first in theaters, then on video and DVD, and now on cable and streaming sites. So when A&E needed a suitable companion series for “Bates Motel,” which is based on another unstoppable horror franchise that has thrived across multiple platforms, it seemed the perfect time to continue the “Omen” saga. And the sinister Mr. Thorn was born … again.