Keegan Allen Talks Toby's Betrayal on 'Pretty Little Liars'

Late last year, we found out that Keegan Allen was a part of the “A” team on Pretty Little Liars — and it shocked us.

The 26-year-old actor sat down with Teen Vogue to answer a few questions about shedding his good-guy persona and what’s going to happen in the second half of the third season. Check it:

On going from good to bad: “We have brilliant writers. Everyone from Marlene King, who developed the show, to Sara Shepard, who wrote the books, to Oliver Goldstick, who runs the show, they all do something very interesting, and that’s pull from the bones of their favorite writers and favorite fictions. With the storyline of Toby, they pulled from the greatest story of all�the betrayal story. And you can’t just betray within the realm of Rosewood, you have to betray the audience. Tobias had been the moral compass of the show; I was shocked.”

On keeping it all a secret: “I knew about it for a very long time. I couldn’t tell my mom, I couldn’t tell anyone! Even Lucy [Hale]. She’ll come to the set on an off day and be like, ‘What’s going on, guys?’ Because, being the little firecracker that she is, she’ll try to figure it out. She came the day that we shot the reveal. They had Tyler, me, and Lindsey Shaw in black hoodies and we all did that turn-around. She was like, ‘Who’s going to be A?’ And I had to be like, ‘I don’t really know.’”

On breaking Troian Bellisario‘s heart: “She finds out in the most heartbreaking way. Even when I was shooting it, I was like, ‘Wow, I’m so upset at my character.’ Troian‘s really good; she was like, ‘Just don’t even look at me.’”

Pretty Little Liars returns NEXT WEEK on ABC Family.