For the leading ladies of ABC’s “Don’t Trust the B in Apt. 23,” the notion of evolving their characters means something different to each.

For Chloe, the “B” in the show’s title means no evolution at all. And that suits actress Krysten Ritter just fine.

“When you sign on for a racy show you always assume it will be watered down, that the character won’t be a bitch anymore,” Ritter says. “That’s not the case here. I’m excited to say my character doesn’t change at all.”

For co-star Dreama Walker, who plays Chloe’s good-girl roommate June, her character has already evolved into thinking its commonplace to be friends with a TV star like James Van Der Beek.

“I really love what the writers are doing between June and James because in the pilot she’s a big ‘Dawson’s Creek’ fan and was enamored with Dawson growing up, but in the last episode she looked at him and said, with disappointment, ‘I used to have a poster of you,’ ” Walker says. “She goes in spurts, realizing these women are self-centered people. She thinks it’s fun sometimes and other times thinks they’re absolutely ridiculous and she’s sick of it.”

Both stars professed their admiration for series creator Nahnatchka Khan. Walker says she shared stories of her own early days in New York living in a basement apartment with seven other people. Her bed was next to the toilet.

“She’s been really wonderful about hearing me out,” Walker says. “There’s a whole episode we did based on a party I brought Nahnatchka and other producers to.”

Ritter declares her own allegiance to Khan.

“I worship the ground she walks on,” she says. “After five minutes of talking to her, I never questioned this show was the right fit for me.”