Speaking to Entertainment Weekly, Gillies explained that the writers have been keeping him "in the dark".
"But you can't really play a character unless you take a guess," he said. "I was like, 'Look, I'm going to make some decisions, and if I'm wrong down the road, then I'll be wrong.
"'But if I don't start making decisions, then it's just going to be this gelatinous entity. It's not going to have any spirit'. I'd rather be wrong but owning my incorrect direction... [But] I think I'm not very far off."
Gillies also revealed that Elijah will start staying in Mystic Falls, saying: "He's really trying to entrench himself and in a sense, he's creating this kind of phalanx around Elena using Damon and Stefan. He's sort of like a military tactician, almost.
"I feel like he, unlike myself, has the patience of a god. I feel like he would wait 100 years to be able to avenge something, a slight on him."
The Vampire Diaries returns for new episodes on January 27 at 8/7c on The CW.