The network’s entertainment president stands by ‘Moonlight’ as it transmogrifies.

“Oh, I love my vampire!” CBS President of Entertainment Nina Tassler said recently, beginning a conversation about her network’s new drama, “Moonlight.”

Clearly, she must. No other TV show this fall has experienced as much turbulence as “Moonlight.” But through all of the changes in the executive producing ranks, the cast and the show’s framework, CBS hasn’t budged in its support, scheduling it in between its reliable Friday-night fare, “Ghost Whisperer” and “Numb3rs.”

Other networks might have postponed the series or decided not to air it, but Tassler, who says she’s always had “affection for the vampire character” and admits she was “smitten” by star Alex O’Loughlin the first time she met him, remains steadfast.

“You have to remember that this is under the auspices of Joel Silver and we’ve got a lot riding on Joel,” Tassler said. “As you continue to work on a show, if I still feel inspired, and I feel they are making exciting choices, then our enthusiasm remains. This is not a perfect science. It’s an evolutionary process.”

In a fall season marked by uncertainty because of a looming writers’ strike and the impact of DVR viewing on ratings, that strategy might pay off.

Although the first two episodes of “Moonlight” were not received well by the critics and the show has not lived up to predecessor “Close to Home,” recent airings have shown more promise. While ABC’s “Women’s Murder Club” is registering more viewers comparatively on Fridays at 9 p.m., “Moonlight” is attracting more 18- to 49-year-olds, the most coveted demographic for advertisers. Of its 8.3 million viewers, 3.1 million are in that age group.

“We’re not out of the woods yet,” Silver said. “We’re just doing OK. We’re kind of slugging through it, and we’re feeling good about where we’re going, and the saga is becoming very clear.”

Although CBS has not picked up a full season of episodes, Tassler ordered four more scripts last week.

“I am pleased,” she said. “I am encouraged. I know we have great episodes ahead. It’s an interesting season. It’s a marathon, not a sprint.”

Flying without a pilot

At the starting line was a script by Trevor Munson, which Silver’s company thought would make a better TV series than a movie. Tassler, who had been searching for a romantic action drama, was instantly interested and asked that Ron Koslow (“Beauty and the Beast”) be paired with Munson to write it.

“I think when you’re talking about a classic genre, the audience is going to come with some level of familiarity so they’re going to know what a vampire does, and I think we didn’t need the whole pilot to create an effective sales tool,” said Tassler, explaining why she ordered a presentation and not a pilot to show advertisers. “And the truth is everybody is shooting pilots at the same time. You’re com- peting for the same talent, the same locations. You’re not always able to get the perfect elements.”

By the time CBS announced its lineup to advertisers at Carnegie Hall in May, David Greenwalt (“Angel”) had been hired to run the show, transform it from a dark, brooding tale to a lighter romance and recast every role except the lead.

Was the star ever in jeopardy?

“No, no, no, no,” Tassler said. “Mick St. John was Alex O’Loughlin. Alex is so warm and genuine and such a wonderfully talented actor. We had seen his episodes of ‘The Shield,’ and he’s got such great charisma and is so unassuming in his crazy good looks that he just endears himself to you.”

A fan of Anne Rice and the genre, the Australian-born O’Loughlin said he couldn’t pass up the chance to play an 85-year-old private investigator that was turned into a vampire by his bride on their wedding night when he was 30. But as the production unraveled, O’Loughlin worried.

“The most unnerved I’ve been in this whole process was when I was at Carnegie Hall by myself on stage,” said O’Loughlin, 32. “There was the cast of ‘Cane,’ like 10 people on stage, and the cast of ‘The Big Bang Theory,’ and I kind of waddled out there by myself and I was like, ‘Please watch “Moonlight.” Bye.’ “

“And I felt like a [jerk] ’cause I didn’t know what was coming. I had lost my entire cast.”

‘Bizarre gestation’

In July, Greenwalt and Silver hired Sophia Myles (“Underworld”) as Beth Turner, the online reporter who falls for Mick after she learns he is a vampire who saved her life when she was a girl; Shannyn Sossamon (“Kiss Kiss Bang Bang”) as Coraline, Mick’s vampire wife; and Jason Dohring (“Veronica Mars”) as Mick’s pal, the 400-year-old vampire Josef Konstantin.

Greenwalt rewrote the first two episodes, helped to promote the show and then dropped a bomb before the revised pilot was complete.

“We were doing pretty well, and David got ill and he just didn’t want to continue on,” Silver said. “He quit.” (Through his manager, Greenwalt declined to be interviewed.)

Four days later, Tassler asked longtime friend Chip Johannessen (“The X-Files” and “Surface”), whom Greenwalt had hired to write one script, to run the show.

“It basically would have shut down if I didn’t do it, and Nina’s been a friend for a long time,” Johannessen said. “This show has had this bizarre gestation, and honestly, it was an opportunity. It just seemed like it was a series of accidents.”

Deathless romance

His first task was to rewrite the first three episodes to highlight the budding romance between a vampire and a mortal, which critics have noted is not an original concept, as well as focus the central theme of the series.

“We’re taking more of a modern, biological approach to it,” Johannessen said. “If you’re going to try to get people to be immortal, what might that look like? There may be some side effects that would be a down side to being a vampire. At the center of this thing is that he’s a reluctant vampire. He wants to hang on to his humanity.”

Mick St. John doesn’t kill or try to turn humans and drinks their blood only when he himself is near death, as he partook from Beth in the fourth episode, intensifying the sexual tension between them. His blood normally comes from the morgue.

“Even if you take the vampire element out of this show, what’s fascinating to me is the concept of his immortality and how that will affect their relationship — falling in love with someone that will never die,” Myles said. “The vampire stuff is very cool, but it’s a love story with such a twist to it, really.”

One of the biggest changes in direction occurred when CBS asked that Beth learn Mick is a vampire at the end of the second episode instead of dragging it out. The change caught O’Loughlin by surprise and “concerned” him at first.

“But then I realized that the stakes are much higher now,” O’Loughlin said. “Honestly, I’m surprised at how together we’ve been able to keep it with the fundamental changes that have happened in the creative positions. It’s been hard to find the rhythm, but I think we’re finding our tone now.”