"Charlotte s gotten a lot better, that s kind of how we open," Sasha Pieterse says

‘A’ framed, kidnapped and tortured Alison DiLaurentis’ best friends on Pretty Little Liars, but the reformed mean girl has made nice with her long-lost sister.

“It’s good and it’s healthy,” Sasha Pieterse, who plays Ali, told PEOPLE on Sunday of her character’s relationship with CeCe Drake aka Charlotte DiLaurentis, who anonymously abused the Liars after being forsaken by her family and institutionalized, secretly transitioning from male to female to get close to those who abandoned her.

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The summer finale saw Ali – and the audience – feeling sympathetic toward Charlotte (Vanessa Ray). And as shown in a clip of the first four minutes of season 6, Ali pleades with everyone to return to Rosewood to testify in Charlotte’s latest hearing five years later.

“Charlotte’s gotten a lot better, that’s kind of how we open. I’m asking the girls to basically come back and approve of Charlotte’s trial to be let out as a normal citizen, which is hard, obviously, it brings a lot of turmoil back,” Pieterse explained at Paleyfest in New York. “It’s interesting to see how all the girls handle each other again because they’re all totally different people now, and this is really their first time coming together again. So it’s surreal and it’s dark and it’s twisted and it’s hard to deal with.”

The end of August’s finale included a flash forward in which Ali, an English teacher, is now “Mrs. Rollins” – and Aria (Lucy Hale), Spencer, (Troian Bellisario), Hanna (Ashley Benson) and Emily (Shay Mitchell) warn that “he’s coming for you.”

Fans won’t see how that scene plays out until later in season 6, but Pieterse said she knows who “he” is – though her lips are sealed. Have viewers seen him before?

“Not yet,” she teased. “Sort of.”

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As for her husband: “When we come back, she’s not married yet so the fans get to see her love story and how it ties in,” Pieterse said. “I think it’s really fun to see her actually have a normal life in a good way. She’s totally changed for the better, she’s come through a lot of therapy, and she totally treats people in a different manner. She’s basically learning through her students, which is nice.”

Plus, the time jump puts Pieterse, 19, in a unique position: Unlike the rest of the stars, who are now playing closer to their actual ages, she’s younger than Ali.

“It’s very ironic,” she said. “I started the show when I was 12, and I was playing 15-ish, and then I was older than my character, and now I’m younger than my character again. So I’ve always kind of had this in my career, but it is, it’s fun. It’s been such a great ride.”