As the show's Paris-era was unlocked, viewers have been introduced to a new supporting cast in Belly's circle in the French capital, including Gemma, who like Belly, is new to Paris.
Brown describes her character as a "kindred spirit" to Belly.
They meet outside a nightclub, when Gemma is being bothered by a man. Belly steps in to help her out and the two become friends.
Brown says it is one of her favourite moments and shows "women supporting each other".
According to Amazon, this season's first episode drew in 25 million global viewers, a 40% increase on the previous season, with Prime Video saying it is its most-watched TV season among women aged 18-34.
Brown thinks the success of the show comes down to the writing by Jenny Han, who wrote the young adult (YA) romance books the TV series is based on.
"She knows what she's doing. She's got everybody hooked from the books," Brown says.
"It's lucky me to be a little part of that."
Brown feels another reason why the show resonates is "because we all go through it".
"We go through friendship, heartache, love, confusion. For the audience that watch this show and love The Summer I Turned Pretty that is a big thing, it's a new thing, it forms so much of your life.
"Being able to watch someone's else experience of that is helpful... and we all love a bit of romance," she says.
Beyond the traditional audience watching on screens, there are countless fan edits and reaction videos posted on social media, which Corinna says have been positive towards her character.
"They've been lovely. I've only seen good things. They say they like Gemma giving her [Belly] straight advice."
Already beloved by YA fans for her turn as Tara Jones in Netflix-hit Heartstopper, Brown is no stranger to the world of teen romance adaptations.
"With any show that's for a young audience, you have to have that awareness of the young minds that you're inspiring, shaping," Brown says.
"And that's an honour in itself."
Amid all the buzz of the show, secrets are tightly guarded and with the finale about to drop we are not allowed to ask Brown what happens in it.
But we can't help but ask what feels to fans like the summer's most pressing question: Are you team Conrad or team Jeremiah?
"I'm going to keep my lips tight on that one," Brown says, smiling.
"But what I will say is I am Team Gemma and Team Belly's friendship forever."