Claudine (Lara Pulver) was killed in the instalment when Eric (Alexander Skarsgård) fed from her.
Harris has now told Entertainment Weekly that she did not expect the twist as Claudine dies much later in her novels.
However, she explained that she trusts True Blood's executive producer Alan Ball, saying: "If he can be gracious to me, I can certainly be gracious enough to wait and see where he's going."
Meanwhile, Ball explained that he wants to diverge from the books slightly to keep the audience guessing.
"If we did just do everything in the books, there would be no surprises," he said. "It's not like we have a formula for what we're going to keep from the books and what we're going to change. If there's a consensus that something makes sense, that's usually the way we go."
Harris recently confirmed that she is planning to end her Southern Vampire Mysteries book series after the 13th novel.
True Blood continues on Sundays at 9pm on HBO.