The actor told TV Guide that his character Stefan has a "contentious relationship" with his brother (Ian Somerhalder).
"I'm sure it'll be [like] a ping-pong game - it's back and forth," he explained. "I think there's definitely going to be hostility [in the next season]."
However, Wesley expressed his hope that the Salvatore brothers will settle their differences for good when The Vampire Diaries comes to an end.
"I hope that the [series] finale of Vampire Diaries - whatever season it may be - ends in them united, as brothers who love each other," he said.
Vampire Diaries star Candice Accola (Caroline) recently admitted that she wants the show's characters to reach their "breaking point" in season four.
"What I am personally excited to see is, what everyone's breaking point is going to be," she admitted. "Because at this point, everyone has really had to keep it together - what is gonna be the straw that starts to break the camel's back?"
The Vampire Diaries will return to Thursdays at 8/7c on The CW this fall. In the UK, the series airs on ITV2.
> The Vampire Diaries: What we want to see in season four