The 36-year-old actress, who has played Sienna since 2012, believes her on-screen character got “desperate” to keep Brody Hudson away from Summer, played by Rhiannon Clements.
She told Metro.co.uk: “She is such a pain to Sienna! Obviously, this girl just showed up at a very inconvenient time, and she just seems to be there all the time. And now Brody loves her, but Sienna has this really strong instinct that everything isn’t what it seems and I think the audience is already in – they already know summer is up to something.
“Sienna is very frustrated. She’s desperate to keep Brody out of the summer, but of course it just says, “Oh, I don’t like your new girlfriend.” But Sienna says, “No, there really is more to it and I know because I’ve been that girl and you have to stay away from her!”
The problem comes to a head this week when Sienna is in serious condition after being shot over the summer.
And Anna finds the plot developed in a really interesting way.
She said, “The perspective we’re telling the story from is that the audience is with Summer and they know what she’s up to, but they know Sienna doesn’t know and they’re waiting for her to catch up on what’s going on is.
“I think that makes the story all the more interesting. So far, Sienna has only viewed summer as a kind of inconvenience, but I don’t think she really saw the darkness that can result from it. So this will be fine when the penny falls. “