They started out as scrappy, 15-year-old Calgary punks, but tomorrow night, Tegan and Sara return to Vancouver as unabashed pop stars.

On The Coast music critic Andrea Warner says the sisters' 20-year musical evolution has taken them a long way from their beginnings as folk fest faves.

"People were intrigued by the optics: Twins! Lesbians! Bandmates! And immediately attempt to shoehorn Tegan and Sara into the queer, folkie, political, girls-with-guitars scene, but they thought they were more in line with Bruce Springsteen," Warner told On The Coast host Stephen Quinn.

The band's indie breakthrough came in 2004 with their record, So Jealous, which Warner calls a more straightforward, indie-rock record, that spawned their first big hit, Walking With A Ghost.

"It's a great breakup song. It's not overly mournful, sort of this attempt at an exorcism, you know, where you're trying to break free," Warner said.

Thanks to that record, they started getting more attention, including internationally. Their songs were frequently used in the TV series Grey's Anatomy.

Warner says the move to a more pop sound wasn't an overnight thing, but it became especially pronounced on 2013's Heartthrob and the lead single Closer.

While the move has generated some fan backlash, Warner says their last album, Love You To Death, is one of their most political and heartfelt records: they're dealing a lot with their own relationships and a lot of deep heartbreak and healing.

"Which challenges the notion that fun music can't also be thought-provoking or challenging," Warner said.

"They're bringing in non-heteronormative relationships, which we don't hear much of in mainstream pop music on the radio, and that's still a really important thing."

Tegan and Sara play at the Queen Elizabeth Theatre in Vancouver on Oct. 5.

With files from CBC Radio One's On The Coast

To hear the full story, click the audio labelled: Tegan and Sara return to Vancouver as different artists from when they started