Toward the end of the latest Tegan and Sara album, Love You to Death, the Canadian sister duo delivers an emotional one-two punch in the form of “White Knuckles” and “100x”. Both songs were primarily written by Sara Quin, revisiting a past self who chafed at feeling constantly joined at the hip to her twin and musical partner.

“I cried wolf/Howled it at the moon,” Sara sings on “White Knuckles”, “So, luck be damned/Break that mirror in two.”

Tegan recalls working on the song with her sister, blissfully unaware that it was inspired by their sometimes fraught relationship. “When I went into the studio when she was finishing that one—I ended up contributing a little bit to the chorus and then wrote the pre-chorus—I was like, ‘Sara’s writing a kick-ass breakup song,’ ” Tegan tells the Straight over the phone from a tour stop in Scottsdale, Arizona. “It really resonated with me. I love the way Sara writes; she’s got this way of really creating an image in your mind, you know? She’s quite poetic in the way she writes. And both ‘100x’ and ‘White Knuckles’ are my favourites. And it’s so funny, I didn’t know until we started promoting the record that the songs are about a very tortured, very early part of our career where we were both fighting for independence. We moved across the country—Sara moved to Montreal. We were attempting a very impossible thing, which was to feel autonomous and independent while sharing everything. There was definitely a struggle.”

That emotional tug of war seems to be a thing of the past; the Tegan and Sara of 2016 present a united front, and the Calgary-born sisters’ shared career has never been stronger. Produced by studio wizard Greg Kurstin (Adele, Taylor Swift), Love You to Death is a strong follow-up to the duo’s commercial breakthrough, 2013’s Heartthrob. The new record finds Tegan and Sara diving even deeper into the synth-pop pool, with tracks like “Boyfriend” and “Stop Desire” barbed with razor-sharp hooks.

What connects the new material to the Quins’ more indie-rock-oriented back catalogue? It’s intangible, but Tegan says it all comes down to feeling. “We felt like every single song on this record should feel like it could have come off The Con or So Jealous—the emotional intensity and vulnerability and rawness of the early Tegan and Sara music should be there. We shouldn’t have to give that up to make a record that could be played on the radio.”

Tegan admits that some long-time fans would prefer that she and Sara return to the sound of those older albums and not just the emotional content. “When people come up and say that to me now, about older records, I hear what they’re saying,” she says. “They liked part of what we represented: we were the fringe, we were the outsiders, we were the alternative. And by trying to reach the mainstream, I know sometimes that challenges our fans, because they still want us to be outsiders. But we also have bigger intentions with our music. It’s about not saying the same thing that we’ve said before. And I think now we want to speak to the mainstream. We want visibility, we want to be represented. We want to activate, you know?”

The Quins are speaking to the mainstream in a big way. From singing their hit single “Closer” with Taylor Swift in 2013 to performing The Lego Movie’s Oscar-nominated “Everything Is Awesome” at the 2015 Academy Awards, Tegan and Sara are a part of pop culture now. It’s a pretty nice payoff for spending so many years under the radar; they self-released their first album, Under Feet Like Ours, in 1999, but for much of the world, Tegan and Sara seem like relative newcomers.

“If there’s a possibility that we can be mistaken for new or fresh, that’s awesome,” says Tegan. “I’ll take it, because after eight records and so many years, you start to worry that you seem like you’re a heritage band or something, which we’re obviously not. We had the benefit of putting out our first record when we were 18. We started in our youth, so we have that on our side. I know lots of friends who are putting out their first record and they’re in their late 20s or early 30s, so we’re lucky that we had so many years out of the limelight to build our career and build our persona and build our craft.”

Asked if her 18-year-old self could have foreseen that she would still be making music alongside her sister in 2016, Tegan admits that she doesn’t think that far ahead. Tegan and Sara have never had a five-year plan, let alone a 17-year one.

“Sara and I wake up every morning and think, ‘This is so cool, we still have a job,’ ” she says. “Our career still feels interesting. We’ve taken risks and therefore really been satisfied on a creative level, an artistic level, so we just kind of focus on that.”

Tegan and Sara play the Queen Elizabeth Theatre on Wednesday (October 5).