Sara Paxton and Melissa Fumero say they loved shocking viewers with their characters' 11th-hour plot twists in Season 2 of Based on a True Story.

Season 2 saw new parents Ava (Kaley Cuoco) and Nathan Bartlett (Chris Messina) investigating a copy-cat murderer whose modus operandi appears to follow that of the recently retired West Side Ripper (Tom Bateman).

After discovering the Ripper was their very own plumber Matt in Season 1, the couple blackmailed him into participating in their true-crime podcast instead of turning him into police.

Matt agreed to stop killing people, but, unfortunately, remains part of Ava's and Nathan's lives because he is engaged to Ava's younger sister Tory, (Liana Liberato), who loves him and wholeheartedly believes he can be reformed.

The Season 2 finale revealed the new serial killer is Paige (Paxton), the demure-seeming sister of one of Matt's Season 1 victims.

Aquamarine and Murder in the First actress Paxton, 36, told UPI in a Zoom interview this week that she was a big fan of Season 1 and had no idea she would be the Season 2 villain until after she read for a different role.

"They didn't tell me anything except that I'm the sister of Chloe Lake (Natalie Dyer), who was murdered in Season 1," she recalled. "So, I went in and I shot my little scene and it wasn't until I was done, that the showrunner and all the producers and the directors kind of gathered round and said, 'OK, we're going to tell you the surprise now!'"

She was thrilled when they told her she would be playing the copycat killer.

"I could have cried," she said. "I was like, 'I'm a serial killer!'"

Paxton's character Paige isn't a woman who finds satisfaction in murdering random people.

Still mourning the death of her sister, she consequently targets people who profit from the misery of crime victims.

"But, also, these podcasters, in her mind, exploited her sister's story for clicks and views," the actress added. "She thinks that they are just as culpable."

The role allowed Paxton to play a lot of emotional notes in a short amount of time.

"Just the grief of something so devastating happening to her sister, someone she's so close with, that's kind of like the driving force behind the character," Paxton said.

"I can empathize with that, so once I was kind of in that, everything else kind of was easy. Not that being the killer is easy, but it's easy to get in that mindset."

While the show is meant to be entertaining, Paxton also hopes it reminds people to focus on the victims not just the perpetrators in real-life murder cases.

"A lot of times when these horrible stories happen in real life, the shift becomes to the killer and they kind of lose sight of the victims," Paxton said.

Relating this back to Based on a True Story, she said Paige not only holds Matt accountable for Chloe's death, but she also blames podcasters, journalists and corporate sponsors of true-crime programs for the "metaphorical death of her sister's character and her spirit afterward."

Also among Paige's victims is real-life actor Jared Leto, who has played murderers in movies.

"The show's just so funny," Paxton chuckled. "I'm reading the scripts and I'm laughing. I just think it's so funny that [it said,] and 'also Jared Leto.' She's pissed. If I had a sister and something like that happened to my sister, who knows?"

For the record, Leto is fine in real life.

Season 2 of Based on a True Story did end, however, with Matt capturing Paige and the door being left open for a possible Season 3 collaboration between the two killers.

Brooklyn Nine Nine and Blockbuster alum Fumero, 42, joined the show's ensemble for Season 2 as the mysterious Drew.

At first, she presents herself as a sympathetic confidante for new mom Ava, but then she appears to be a homicide detective investigating the copycat killer and eventually seems like she might be the murderer herself.

It isn't until almost the end of the season -- and moments before Tory kills her -- that viewers learn she is actually Matt's ex-wife, Olivia.

"They were really generous in that they told me all the twists and turns of Drew before I started, which I think was really valuable information for me to have. Sometimes, writers won't always choose to give actors that info and, so, you're just kind of playing a big secret at all times," Fumero told UPI in a separate Zoom interview.

"It was really fun to know and be able to pick specific moments to play her secrets," she added. "You know there's something about her you can't put your finger on."

Fumero is not a true-crime fan herself in real life, but she liked the way the show satirizes some people's obsession with this entertainment sub-culture.

"I just thought the approach of the show and how it does that is really clever and fun to watch," Fumero said.

"These things exist and they're out there in the whole social media/Tik Tok universe and these little niche genres can get intense. It's fun to have a show that examines that."

Just because Olivia is dead doesn't mean she might not be part of a third season via flashbacks that explore what her life with Matt was like before they split up, Fumero teased.

"Who knows?" Fumero said. "Listen, I love the show. I love everyone that works there. If they want me to come back and do anything, I'll be very happy, so, it's in their hands."