Speaking to the New York Post, Preston revealed that she has loved her pregnancy storyline in the show's third season.
"I got really excited about it because when they give you a storyline - some kind of conflict or obstacle - you know the writers have something to work with," she said.
Preston explained that Arlene has struggled to come to terms with the fact that she is carrying Rene's baby, saying: "Arlene is kind of a superstitious person. She's someone who takes things at face value and to be pregnant with an evil person's baby is not something she's comfortable with.
"You've now seen the dilemma she's presented with and that carries us through [the last few] episodes - she has some solutions presented to her and big choices to make."
Preston also revealed that she loves exploring Arlene's personality in depth.
"It's always nice to play someone who knows what they want, why they want it and what their attitudes are towards life," she said. "It just makes your job, as an actor, clearer. I also feel responsible, as a Southern woman, for giving her depth that might not be on the page.
"As written, she could be set up as someone to be ridiculed - it's easy to stereotype her. I try to play against that. To have her come from a place of reality instead of being some fictitious stereotype of the average southern racist. We've seen that a million times."
True Blood continues on Sundays at 9pm on HBO.