First, we have to ask about Angel. What’s your fave episode of the show? (Mine is ‘Smile Time’.)

Oh, yeah. ‘Smile Time’ had some of my most favourite memories of Andy Hallett. Actually, we got in pretty big trouble because we could not stop laughing for three hours. Every time I think back on him and the show, I do remember that episode. And probably ‘Hole In The World’ because Joss [Whedon] wrote and directed it, and he was there. We had a super long hard day filming where Fred eventually turns into Illyria, and afterwards we went to get a drink. We all just sat there drinking and no one said a word and Joss said that’s where he came up with the ending for Avengers after that night.

So, fast forward to today and your role as Root on Person of Interest. Did you ever think your character would be so popular?

It was such a surprise, really. They asked me if I would come and do five or six episodes, so I really thought that was all it was going to be. I thought I was going to be the bad guy and that was the arc of the character for the season. I just felt so lucky that they asked me to stick around and got to become part of the scene. It was unexpected and wonderful.

On the show, milestones have been hinted at in past seasons, so what can you tease about season five?

I think it really picks up where we left in season four. Root is struggling with finding Shaw versus stopping Samaritan and which one comes first. It’s a nice arc to play and see how it affects her and how it affects the rest of the team.

So, can you describe season five in three words?

Let’s see. Unexpected… Oh, this is hard! Sexy. And, um… What’s something that would mean happy and sad at the same time?

Bittersweet?

Yes, bittersweet. I like that. Let’s go with that.

Are there any difficulties or challenges with playing Root?

I think it’s such a blessing that we have such amazing writers on the show. They always give you all these tools you need to get to the place you need to get to in the scene. I’ve definitely had to do some weird things! I needed to start working out, because I’m kind of lazy that way, and I found out that when you need to hold up two guns for a really long time it’s really hard. [Laughs] It’s always challenging because I’m not a tech-savvy person so I’ve had to do a lot of research and it’s really fascinating to see, because the writers are so smart and know so much about things that are happening. I’ve been on shows where there are demons and made-up things, so it’s like, ‘Oh, if they are talking about that, it must be made up,’ and they’re like, ‘No, that’s a real thing.’ So I had to do a lot of learning on technology and computer viruses.

What makes a good scene partner?

Maybe if their name is Michael Emerson that’s a good start. [Laughs] I’ve been so lucky. I just think back to Angel to work with J. August Richards and Alexis. I just think when you have a good scene partner, like J. or Alexis or Michael, or everyone on Alias, it seems like the writers get excited about that as well, and they tend to write you really cool scenes that you both get excited about as well. I feel like a good scene partner for me is someone I learn something from every time I’m in a scene with them.

Do you have upcoming projects you can share with us?

I’m doing a movie in Texas in May and that should be really fun. And I’ve been working on writing some stuff as well. I’ve just been taking some time to work out what I want to do next. I feel like I’m spoiled when I’m on these shows with people like Joss Whedon and J.J. Abrams, so I’ve been picky about what I want to do next.

What’s your favourite dessert?

That’s a good question. There’s so many! We just got a pie yesterday for Pi Day and I chose a random salty honey pie that the kids didn’t like, so I have to eat a whole pie by myself. But a good pie is always good. I’m a huge caramel fan and a huge chocolate mint fan. My all-time go-to favourite thing is a place in New York called Milk Bar and they have this delicious thing called Crack Pie, so it’s pretty much that.

Amy Acker is at Supanova Pop Culture Expo, on April 8-10 in the Gold Coast, and April 15-17 in Melbourne. Get your tickets here.